The Neo4j Manual v1.4

The Neo4j Manual v14M06

The Neo4j Team neo4jorg lthttpneo4jorggtneotechnologycom lthttpneotechnologycomgt

The Neo4j Manual v14M06by The Neo4j Team neo4jorg lthttpneo4jorggt neotechnologycom lthttpneotechnologycomgtCopyright copy 2011 Neo Technology

License Creative Commons 30This book is presented in open source and licensed through Creative Commons 30 You are free to copy distribute transmit andor adapt the work Thislicense is based upon the following conditions

Attribution You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or youruse of the work)

Share Alike If you alter transform or build upon this work you may distribute the resulting work only under the same similar or a compatible license

Any of the above conditions can be waived if you get permission from the copyright holder

In no way are any of the following rights affected by the license

bull Your fair dealing or fair use rights

bull The authorrsquos moral rights

bull Rights other persons may have either in the work itself or in how the work is used such as publicity or privacy rights

NoteFor any reuse or distribution you must make clear to the others the license terms of this work The best way to do this is with a direct link tothis page httpcreativecommonsorglicensesby-sa30 lthttpcreativecommonsorglicensesby-sa30gt

Table of ContentsIntroduction viii

1 Who should read this ix2 Neo4j highlights x

I Reference Documentation 11 Installation amp Deployment 2

11 Deployment Scenarios 312 System Requirements 413 Installation 514 Upgrading 715 Usage Data Collector 9

2 Configuration amp Performance 1121 Caches in Neo4j 1222 JVM Settings 1723 File system tuning for high IO 1824 Compressed storage of short strings 19

3 Transaction management 2031 Interaction cycle 2132 Isolation levels 2233 Default locking behavior 2334 Deadlocks 2435 Delete semantics 25

4 Cypher Query Language 2641 Identifiers 2842 Start 2943 Match 3144 Where 3445 Return 3646 Aggregation 3847 Order by 4148 Skip 4349 Limit 44

5 Neo4j Server 4551 Server Installation 4652 Server Configuration 4853 Setup for remote debugging 5054 Starting the Neo4j server in high availability mode 5155 Using the server with an embedded database 5356 Server Plugins 5457 Tuning the server performance 5758 Unmanaged Extensions 58

6 REST API 6061 Service root 6162 Nodes 6263 Relationships 6664 Relationship types 7065 Node properties 7166 Relationship properties 74

67 Indexes 7568 Traversals 7969 Built-in Graph Algorithms 105610 Batch operations 108611 Gremlin Plugin 113612 Cypher Plugin 118

7 Indexing 11971 Introduction 12072 Create 12173 Delete 12274 Add 12375 Remove 12476 Update 12577 Search 12678 Relationship indexes 12879 Scores 129710 Configuration and fulltext indexes 130711 Extra features for Lucene indexes 131712 Batch insertion 133713 Auto Indexing 134

8 Graph Algorithms 13881 Introduction 139

9 High Availability 14091 Architecture 14192 Setup and configuration 14293 How Neo4j HA operates 144

10 Operations 145101 Backup 146102 Security 148103 Monitoring 149

II Tutorials 15411 Graph Database Concepts 155

111 What is a Graph Database 156112 Comparing Database Models 160113 The Neo4j Graph Database 163

12 Using Neo4j embedded in Java applications 167121 Include Neo4j in your project 168122 Hello world 170123 User database with index 172124 Traversal 174125 Domain entities 183126 Graph Algorithm examples 184127 Reading a management attribute 186

III Tools 18713 Web Administration 188

131 Dashboard tab 189132 Data tab 190133 Console tab 191134 The Server Info tab 193

14 Neo4j Shell 194141 Starting the shell 195142 Passing options and arguments 197143 Enum options 198144 Filters 199145 Node titles 200146 How to use (individual commands) 201147 Extending the shell Adding your own commands 204148 An example shell session 205

IV Troubleshooting 20615 Troubleshooting guide 20716 Community support 208

A Manpages 209neo4j 210neo4j-shell 212neo4j-coordinator 214neo4j-coordinator-shell 215

List of Figures51 Neo4j Coordinator MBeans View 5291 Typical setup when running multiple Neo4j instances in HA mode 141101 Connecting JConsole to the Neo4j Java process 149102 Neo4j MBeans View 150111 RDBMS 160112 Graph Database as RDBMS 160113 Key-Value Store 161114 Graph Database as Key-Value Store 161115 Document Store 162116 Graph Database as Document Store 162121 Node space view of users 172122 Matrix node space view 174123 User roles node space view 175124 The example graph 179125 Social network data model 180126 Andreas Kolleggers status updates 181131 Web Administration Dashboard 189132 Entity charting 189133 Status indicator panels 189134 Browsing and manipulating data 190135 Editing properties 190136 Traverse data with Gremlin 191137 Query data with Cypher 191138 Interact over HTTP 192139 JMX Attributes 193

List of Tables11 Neo4j deployment options 312 Neo4j editions 521 Guidelines for heap size 1751 neo4j-wrapperconf JVM tuning properties 5771 Lucene indexing configuration parameters 13091 HighlyAvailableGraphDatabase configuration parameters 143101 MBeans exposed by the Neo4j Kernel 150102 MBean Memory Mapping 151103 MBean Locking 151104 MBean Transactions 151105 MBean Cache 151106 MBean Configuration 151107 MBean Primitive count 152108 MBean XA Resources 152109 MBean Store file sizes 1521010 MBean Kernel 1531011 MBean High Availability 153111 Using relationship direction and type 164112 Property value types 165

Introduction

This is a reference manual The material is practical technical and focused on answering specificquestions It addresses how things work what to do and what to avoid to successfully run Neo4j in aproduction environment After a brief introduction each topic area assumes general familiarity as itaddresses the particular details of Neo4j

The goal is to be thumb-through and rule-of-thumb friendly

Each section should stand on its own so you can hop right to whatever interests you When possiblethe sections distill rules of thumb which you can keep in mind whenever you wander out of thehouse without this manual in your back pocket

Introduction

1 Who should read thisThe topics should be relevant to architects administrators developers and operations personnel Youshould already know about Neo4j and using graphs to store data If you are completely new to Neo4jplease check out httpneo4jorg first

Introduction

2 Neo4j highlightsAs a robust scalable and high-performance database Neo4j is suitable for lightweight projects or fullenterprise deployment

It features

bull true ACID transactions

bull high availability

bull scales to billions of nodes and relationships

bull high speed querying through traversals

Proper ACID behavior is the foundation of data reliability Neo4j enforces that all mutating operationsoccur within a transaction guaranteeing consistent data This robustness extends from single instanceembedded graphs to multi-server high availability installations For details see Chapter 3 Transactionmanagement

Reliable graph storage can easily be added to any application A property graph can scale in sizeand complexity as the application evolves with little impact on performance Whether starting newdevelopment or augmenting existing functionality Neo4j is only limited by physical hardware

A single server instance can handle a graph of billions of nodes and relationships When datathroughput is insufficient the graph database can be distributed among multiple servers in a highavailability configuration See Chapter 9 High Availability to learn more

The graph database storage shines when storing richly-connected data Querying is performed throughtraversals which can perform millions of joins per second

Part I Reference Documentation

Chapter 1 Installation amp Deployment

Installation amp Deployment

11 Deployment ScenariosNeo4j can be embedded into your application run as a standalone server or deployed on severalmachines to provide high availability

Table 11 Neo4j deployment options

Single Instance Multiple Instances

Embedded EmbeddedGraphDatabase HighlyAvailableGraphDatabase

Standalone Neo4j Server Neo4j Server highavailability mode

111 ServerNeo4j is normally accessed as a standalone server either directly through a REST interface or througha language-specific driver More information about Neo4j server is found in Chapter 5 Neo4j ServerFor running the server in high availability mode see Section 54 ldquoStarting the Neo4j server in highavailability moderdquo

112 EmbeddedNeo4j can be embedded directly in a server application by including the appropriateJava libraries When programming you can refer to the GraphDatabaseServicelthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdb

GraphDatabaseServicehtmlgt API To switch from a single instance to multiplehighly available instances simply switch from the concrete EmbeddedGraphDatabaselthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jkernel

EmbeddedGraphDatabasehtmlgt to the HighlyAvailableGraphDatabase lthttpcomponentsneo4jorgneo4j-enterprise14M06apidocsorgneo4jkernel

HighlyAvailableGraphDatabasehtmlgt

12 System RequirementsMemory constrains graph size disk IO constrains readwrite performance as always

121 CPUPerformance is generally memory or IO bound for large graphs and compute bound for graphs whichfit in memory

MinimumIntel 486

RecommendedIntel Core i7

122 MemoryMore memory allows even larger graphs but runs the risk of inducing larger Garbage Collectionoperations

Minimum1GB

Recommended4-8GB

123 DiskAside from capacity the performance characteristics of the disk are the most important when selectingstorage

MinimumSCSI EIDE

RecommendedSSD w SATA

124 FilesystemFor proper ACID behavior the filesystem must support flush (fsync fdatasync)

Minimumext3 (or similar)

Recommendedext4 ZFS

125 SoftwareNeo4j is Java-based

Java16+

Operating SystemsLinux Windows XP Mac OS X

13 InstallationNeo4j can be installed as a server running either as a headless application or system service For Javadevelopers it is also possible to use Neo4j as a library embedded in your application

For information on installing Neo4j as a server see Section 51 ldquoServer Installationrdquo

The following table outlines the available editions and their names for use with dependencymanagement tools

TipFollow the links in the table for details on dependency configuration with Apache MavenApache Buildr Apache Ivy and Groovy Grape

Table 12 Neo4j editions

Edition Dependency Description License

Community orgneo4jneo4j lthttpsearchmavenorgsearch|gav|1|g3A22orgneo4j2220AND20a3A22neo4j22gt

a high performancefully ACIDtransactional graphdatabase

Advanced orgneo4jneo4j-advanced lthttpsearchmavenorgsearch|gav|1|g3A22orgneo4j2220AND20a3A22neo4j-advanced22gt

adding advancedmonitoring

AGPLv3

Enterprise orgneo4jneo4j-enterprise lthttpsearchmavenorgsearch|gav|1|g3A22orgneo4j2220AND20a3A22neo4j-enterprise22gt

adding online backupand High Availabilityclustering

AGPLv3

NoteThe listed dependeices do not contain the implementation but pulls it in transitively

For more information regarding licensing see the Licensing Guide lthttpneo4jorglicensing-guidegt

131 Embedded InstallationThe latest release is always available from httpneo4jorgdownload included as part of the Neo4jdownload packages After selecting the appropriate version for your platform embed Neo4j in yourJava application by including the Neo4j library jars in your build Either take the jar files from the lib

directory of the download or directly use the artifacts available from Maven Central Repository 1Stable and milestone releases are available there

For information on how to use Neo4j as a dependency with Maven and other dependencymanagement tools see the following table

NoteThe listed dependencies do not contain the implementation but pulls it in transitively

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltgroupIdgtorgneo4jltgroupIdgt

ltartifactIdgtneo4jltartifactIdgt

ltversiongt$neo4j-versionltversiongt

ltdependencygt

ltdependenciesgt

ltprojectgt

Where $neo4j-version is the intended version and the artifactId is one of neo4j neo4j-advanced neo4j-enterprise

1httprepo1mavenorgmaven2orgneo4j

14 UpgradingNormally a properly shutdown Neo4j database can be upgraded directly to a new minor version Adatabase can be upgraded from a minor version to the next eg 11 ndashgt 12 and 12 ndashgt 13 but youcan not jump directly from 11 ndashgt 13 The upgrade process is a one way step databases cannot bedowngraded

However some upgrades make significant changes to the database store Neo4j will refuse to startwhen a significant upgrade is required requiring explicit upgrade configuration

141 Normal UpgradeTo perform a normal upgrade (for minor changes to the database store)

1 download the newer version of Neo4j2 cleanly shutdown the database to upgrade if it is running3 startup the database with the newer version of Neo4j

142 Special UpgradeTo perform a special upgrade (for significant changes to the database store)

1 make sure the database you are upgrading has been cleanly shut down2 set the Neo4j configuration parameter allow_store_upgrade=true3 start the database4 the upgrade will happen during startup and the process is done when the database has been

successfully started5 allow_store_upgrade=true configuration parameter should be removed set to false or

commented out

143 Upgrade 13 ndashgt 14

WarningUpgrading from 13 ndashgt 14 is done automatically but will in that process upgrade Luceneindexes to Lucene version 310 That Lucene index upgrade is irreversible

144 Upgrade 13M03 ndashgt 13M04

WarningUpgrading from 13M03 ndashgt 13M04 must be done explicitly since store format haschanged between those two versions

The store format as well as logical log format have changed between these two versions to allow forbigger stores

WarningUpgrading from 12 ndashgt 13 must be done explicitly since store format has changed betweenthose two versions

ImportantAlthough id ranges has been increased the space used to store the database will notincrease compared to the previous version

Upgrading between these two version needs to be performed explicitly using a configurationparameter at startup (see Special Upgrade)

CautionUpgrade cannot be performed if either the number of relationship types or the configuredblock size for either the dynamic array store or string store is greater than 65534

CautionIndexes created using the old IndexServiceLuceneIndexService are no longer accessibleout of the box in 13 in favor of the integrated index An automatic upgrade isnrsquot possibleso a full rebuild of the index data into the integrated index framework is requiredFor reference the legacy index can be downloaded from the Neo4j repository httpm2neo4jorgorgneo4jneo4j-legacy-index

146 Upgrade 11 ndashgt 12Upgrading from Neo4j 11 to Neo4j 12 is a normal upgrade

15 Usage Data CollectorThe Neo4j Usage Data Collector is a sub-system that gathers usage data reporting it to the UDC-server at udcneo4jorg It is easy to disable and does not collect any data that is confidential Formore information about what is being sent see below

The Neo4j team uses this information as a form of automatic effortless feedback from the Neo4jcommunity We want to verify that we are doing the right thing by matching download statistics withusage statistics After each release we can see if there is a larger retention span of the server software

The data collected is clearly stated here If any future versions of this system collect additional datawe will clearly announce those changes

The Neo4j team is very concerned about your privacy We do not disclose any personally identifiableinformation

151 Technical InformationTo gather good statistics about Neo4j usage UDC collects this information

bull Kernel version - the build number and if there are any modifications to the kernel

bull Store id - it is a randomized globally unique id created at the same time a database is created

bull Ping count - UDC holds an internal counter which is incremented for every ping and reset for everyrestart of the kernel

bull Source - this is either neo4j or maven If you downloaded Neo4j from the Neo4j website itrsquosneo4j if you are using Maven to get Neo4j it will be maven

bull Java version - the referrer string shows which version of Java is being used

After startup UDC waits for ten minutes before sending the first ping It does this for two reasonsfirst we donrsquot want the startup to be slower because of UDC and secondly we want to keep pingsfrom automatic tests to a minimum The ping to the UDC servers is done with a HTTP GET

152 How to disable UDCWersquove tried to make it extremely easy to disable UDC In fact the code for UDC is not even includedin the kernel jar but as a completely separate component

There are three ways you can disable UDC

1 The easiest way is to just remove the neo4j-udc-jar file By doing this the kernel will not loadUDC and no pings will be sent

2 If you are using Maven and want to make sure that UDC is never installed in your system adependency element like this will do that

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltartifactIdgtneo4j-udcltartifactIdgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Where $neo4j-version is the Neo4j version in use

3 Lastly if you are using a packaged version of Neo4j and do not want to make any change tothe jars a system property setting like this will also make sure that UDC is never activated -Dneo4jextudcdisable=true

Chapter 2 Configuration amp Performance

In order to get optimum performance out of Neo4j for your application there are a few parameters thatcan be tweaked The two main components that can be configured are the Neo4j caches and the JVMthat Neo4j runs in The following sections describe how to tune these

Configuration amp Performance

21 Caches in Neo4jNeo4j utilizes two different types of caches A file buffer cache and an object cache The file buffercache caches the storage file data in the same format as it is stored on the durable storage mediaThe object cache caches the nodes relationships and properties in a format that is optimized for hightraversal speeds and transactional mutation

211 File buffer cache

Quick info

bull The file buffer cache is sometimes called low level cache or file system cachebull It caches the Neo4j data as stored on the durable mediabull It uses the operating system memory mapping features when possiblebull Neo4j will configure the cache automatically as long as the heap size of the JVM is

configured properly

The file buffer cache caches the Neo4j data in the same format as it is represented on the durablestorage media The purpose of this cache layer is to improve both read and write performance Thefile buffer cache improves write performance by writing to the cache and deferring durable write untilthe logical log is rotated This behavior is safe since all transactions are always durably written to thelogical log which can be used to recover the store files in the event of a crash

Since the operation of the cache is tightly related to the data it stores a short description of the Neo4jdurable representation format is necessary background Neo4j stores data in multiple files and relieson the underlying file system to handle this efficiently Each Neo4j storage file contains uniform fixedsize records of a particular type

Store file Record size Contents

nodestore 9 B Nodes

relstore 33 B Relationships

propstore 25 B Propertiesfor nodes andrelationships

stringstore 133 B Values of stringproperties

arraystore 133 B Values of arrayproperties

For strings and arrays where data can be of variable length data is stored in one or more 120Bchunks with 13B record overhead The sizes of these blocks can actually be configured when thestore is created using the string_block_size and array_block_size parameters The size of eachrecord type can also be used to calculate the storage requirements of a Neo4j graph or the appropriatecache size for each file buffer cache Note that some strings can be stored without using the stringstore see Section 24 ldquoCompressed storage of short stringsrdquo

Neo4j uses multiple file buffer caches one for each different storage file Each file buffer cachedivides its storage file into a number of equally sized windows Each cache window contains an evennumber of storage records The cache holds the most active cache windows in memory and tracks hit

vs miss ratio for the windows When the hit ratio of an uncached window gets higher than the missratio of a cached window the cached window gets evicted and the previously uncached window iscached instead

Configuration

Parameter Possible values Effect

use_memory_mapped_buffers true or false If set to true Neo4j will usethe operating systems memorymapping functionality for thefile buffer cache windows If setto false Neo4j will use its ownbuffer implementation In this casethe buffers will reside in the JVMheap which needs to be increasedaccordingly The default value forthis parameter is true except onWindows

neostore nodestore db

mapped_memory

The maximum amount of memoryto use for the file buffer cache ofthe node storage file

neostore relationshipstore

db mapped_memory

The maximum amount of memoryto use for the file buffer cache ofthe relationship store file

neostore propertystore db

index keys mapped_memory

The maximum amount of memoryto use for the file buffer cache ofthe something-something file

index mapped_memory

mapped_memory

The maximum amount of memoryto use for the file buffer cache ofthe property storage file

strings mapped_memory

The maximum amount of memoryto use for the file buffer cache ofthe string property storage file

arrays mapped_memory

The maximum amount ofmemory to use for memorymapped buffers for this filebuffer cache The defaultunit is MiB for other unitsuse any of the following

suffixes B k M or G

The maximum amount of memoryto use for the file buffer cache ofthe array property storage file

string_block_size

The number ofbytes per block

Specifies the block size for storingstrings This parameter is onlyhonored when the store is createdotherwise it is ignored Note thateach character in a string occupiestwo bytes meaning that a blocksize of 120 (the default size) willhold a 60 character long string

before overflowing into a secondblock Also note that each blockcarries an overhead of 13 bytesThis means that if the block size is120 the size of the stored recordswill be 133 bytes

array_block_size Specifies the block size for storingarrays This parameter is onlyhonored when the store is createdotherwise it is ignored The defaultblock size is 120 bytes and theoverhead of each block is the sameas for string blocks ie 13 bytes

dump_configuration true or false If set to true the currentconfiguration settings will bewritten to the default systemoutput mostly the console or thelogfiles

When memory mapped buffers are used (use_memory_mapped_buffers = true) the heap size ofthe JVM must be smaller than the total available memory of the computer minus the total amountof memory used for the buffers When heap buffers are used (use_memory_mapped_buffers =false) the heap size of the JVM must be large enough to contain all the buffers plus the runtime heapmemory requirements of the application and the object cache

When reading the configuration parameters on startup Neo4j will automatically configure theparameters that are not specified The cache sizes will be configured based on the available memoryon the computer how much is used by the JVM heap and how large the storage files are

212 Object cache

Quick info

bull The object cache is sometimes called high level cache

bull It caches the Neo4j data in a form optimized for fast traversal

The object cache caches individual nodes and relationships and their properties in a form that isoptimized for fast traversal of the graph The content of this cache are objects with a representationgeared towards supporting the Neo4j object API and graph traversals Reading from this cache is 5 to10 times faster than reading from the file buffer cache This cache is contained in the heap of the JVMand the size is adapted to the current amount of available heap memory

Nodes and relationships are added to the object cache as soon as they are accessed The cachedobjects are however populated lazily The properties for a node or relationship are not loaded untilproperties are accessed for that node or relationship String (and array) properties are not loaded untilthat particular property is accessed The relationships for a particular node is also not loaded until therelationships are accessed for that node Eviction from the cache happens in an LRU manner when thememory is needed

Configuration

The main configuration parameter for the object cache is the cache_type parameter This specifieswhich cache implementation to use for the object cache The available cache types are

cache_type Description

none Do not use a high level cache No objects will be cached

soft Provides optimal utilization of the available memory Suitable for high performancetraversal May run into GC issues under high load if the frequently accessed parts ofthe graph does not fit in the cache

This is the default cache implementation

weak Provides short life span for cached objects Suitable for high throughput applicationswhere a larger portion of the graph than what can fit into memory is frequentlyaccessed

strong This cache will cache all data in the entire graph It will never release memory heldby the cache Provides optimal performance if your graph is small enough to fit inmemory

Heap memory usage

This table can be used to calculate how much memory the data in the object cache will occupy on a64bit JVM

Object Size Comment

344 B Size for each node (not counting its relationships or properties)

48 B Object overhead

136 B Property storage (ArrayMap 48B HashMap 88B)

136 B Relationship storage (ArrayMap 48B HashMap 88B)

24 B Location of first next set of relationships

208 B Size for each relationship (not counting its properties)

Relationship

116 B Size for each property of a node or relationship

32 B Data element - allows for transactional modification and keeps trackof on disk location

48 B Entry in the hash table where it is stored

12 B Space used in hash table accounts for normal fill ratio

Property

24 B Property key index

108 B Size for each relationship type for a node that has a relationship ofthat type

48 B Collection of the relationships of this type

Relationships

Object Size Comment

Relationships 8 B Space used by each relationship related to a particular node (bothincoming and outgoing)

Primitive 24 B Size of a primitive property value

String 64+B Size of a string property value 64 + 2len(string) B (64 bytesplus two bytes for each character in the string)

22 JVM SettingsProperly configuring memory utilization of the JVM is crucial for optimal performance As anexample a poorly configured JVM could spend all CPU time performing garbage collection (blockingall threads from performing any work) Requirements such as latency total throughput and availablehardware have to be considered to find the right setup In production Neo4j should run on a multicoreCPU platform with the JVM in server mode

221 Configuring heap size and GCA large heap allows for larger node and relationship caches mdash which is a good thing mdash but largeheaps can also lead to latency problems caused by full garbage collection The different high levelcache implementations available in Neo4j together with a suitable JVM configuration of heap size andgarbage collection (GC) should be able to handle most workloads

The default cache (soft reference based LRU cache) works best with a heap that never gets full agraph where the most used nodes and relationships can be cached If the heap gets too full there is arisk that a full GC will be triggered the larger the heap the longer it can take to determine what softreferences should be cleared

Using the strong reference cache means that all the nodes and relationships being used must fit in theavailable heap Otherwise there is a risk of getting out-of-memory exceptions The soft reference andstrong reference caches are well suited for applications were the overal throughput is important

The weak reference cache basically needs enough heap to handle the peak load of theapplication mdash peak load multiplied by the average memory required per request It is well suited forlow latency requirements were GC interuptions are not acceptable

When running Neo4j on Windows keep in mind that the memory mapped buffers are allocated onheap by default so need to be taken into consideration when determining heap size

Table 21 Guidelines for heap size

Number ofprimitives

RAM size Heapconfiguration

Reserved RAMfor the OS

10M 2GB 512MB the rest

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

The recommended garbage collector to use when running Neo4j in production is the Concurrent Markand Sweep Compactor turned on by supplying -XX+UseConcMarkSweepGC as a JVM parameter

23 File system tuning for high IOIn order to support the high IO load of small transactions from a database the underlying file systemshould be tuned Symptoms for this are low CPU load with high iowait In this case there are a coupleof tweaks possible on Linux systems

bull Disable access-time updates noatimenodiratime flags for disk mount command or in the etcfstab for the database disk volume mount

bull Tune the IO scheduler for high disk IO on the database disk

24 Compressed storage of short stringsNeo4j will classify your strings and store them accordingly If a string is classified as a short string itwill be stored without indirection in the property store This means that there will be no string recordscreated for storing that string Additionally when no string record is needed to store the propertyit can be read and written in a single lookup This leads to improvements in performance and lowerstorage overhead

For a string to be classified as a short string one of the following must hold

bull It is encodable in UTF-8 or Latin-1 7 bytes or less

bull It is alphanumerical and 10 characters or less (9 if using accented european characters)

bull It consists of only upper case or only lower case characters including the punctuation charactersspace underscore period dash colon or slash Then it is allowed to be up to 12 characters

bull It consists of only numerical characters inlcuding the punctuation characters plus comma singlequote space period or dash Then it is allowed to be up to 15 characters

Chapter 3 Transaction management

In order to fully maintain data integrity and ensure good transactional behavior Neo4j supports theACID properties

bull atomicity - if any part of a transaction fails the database state is left unchanged

bull consistency - any transaction will leave the database in a consistent state

bull isolation - during a transaction modified data cannot be accessed by other operations

bull durability - the DBMS can always recover the results of a committed transaction

Specifically

bull All modifications to Neo4j data must be wrapped in transactions

bull The default isolation level is READ_COMMITTED

bull Data retrieved by traversals is not protected from modification by other transactions

bull Non-repeatable reads may occur (ie only write locks are acquired and held until the end of thetransaction)

bull One can manually acquire write locks on nodes and relationships to achieve higher level ofisolation (SERIALIZABLE)

bull Locks are acquired at the Node and Relationship level

bull Deadlock detection is built into the core transaction management

Transaction management

31 Interaction cycleAll write operations that work with the graph must be performed in a transaction Transactions arethread confined and can be nested as ldquoflat nested transactionsrdquo Flat nested transactions means thatall nested transactions are added to the scope of the top level transaction A nested transaction canmark the top level transaction for rollback meaning the entire transaction will be rolled back To onlyrollback changes made in a nested transaction is not possible

When working with transactions the interaction cycle looks like this

1 Begin a transaction

2 Operate on the graph performing write operations

3 Mark the transaction as successful or not

4 Finish the transaction

It is very important to finish each transaction The transaction will not release the locks or memoryit has acquired until it has been finished The idiomatic use of transactions in Neo4j is to use a try-finally block starting the transaction and then try to perform the write operations The last operationin the try block should mark the transaction as successful while the finally block should finish thetransaction Finishing the transaction will perform commit or rollback depending on the successstatus

CautionAll modifications performed in a transaction are kept in memory This means that verylarge updates have to be split into several top level transactions to avoid running out ofmemory It must be a top level transaction since splitting up the work in many nestedtransactions will just add all the work to the top level transaction

In an environment that makes use of thread pooling other errors may occur when failing to finish atransaction properly Consider a leaked transaction that did not get finished properly It will be tiedto a thread and when that thread gets scheduled to perform work starting a new (what looks to be a)top level transaction it will actually be a nested transaction If the leaked transaction state is ldquomarkedfor rollbackrdquo (which will happen if a deadlock was detected) no more work can be performed on thattransaction Trying to do so will result in error on each call to a write operation

32 Isolation levelsBy default a read operation will read the last committed value unless a local modification within thecurrent transaction exist The default isolation level is very similar to READ_COMMITTED reads do notblock or take any locks so non-repeatable reads can occur It is possible to achieve a stronger isolationlevel (such as REPETABLE_READ and SERIALIZABLE) by manually acquiring read and write locks

33 Default locking behavior

bull When adding changing or removing a property on a node or relationship a write lock will be takenon the specific node or relationship

bull When creating or deleting a node a write lock will be taken for the specific node

bull When creating or deleting a relationship a write lock will be taken on the specific relationship andboth its nodes

The locks will be added to the transaction and released when the transaction finishes

34 DeadlocksSince locks are used it is possible for deadlocks to happen Neo4j will however detect any deadlock(caused by acquiring a lock) before they happen and throw an exception Before the exception isthrown the transaction is marked for rollback All locks acquired by the transaction are still being heldbut will be released when the transaction is finished (in the finally block as pointed out earlier) Oncethe locks are released other transactions that were waiting for locks held by the transaction causing thedeadlock can proceed The work performed by the transaction causing the deadlock can then be retriedby the user if needed

Experiencing frequent deadlocks is an indication of concurrent write requests happening in such away that it is not possible to execute them while at the same time live up to the intended isolationand consistency The solution is to make sure concurrent updates happen in a reasonable way Forexample given two specific nodes (A and B) adding or deleting relationships to both these nodes inrandom order for each transaction will result in deadlocks when there are two or more transactionsdoing that concurrently One solution is to make sure that updates always happens in the same order(first A then B) Another solution is to make sure that each threadtransaction does not have anyconflicting writes to a node or relationship as some other concurrent transaction This can for examplebe achieved by letting a single thread do all updates of a specific type

ImportantDeadlocks caused by the use of other synchronization than the locks managed byNeo4j can still happen Since all operations in the Neo4j API are thread safe unlessspecified otherwise there is no need for external synchronization Other code that requiressynchronization should be synchronized in such a way that it never performs any Neo4joperation in the synchronized block

35 Delete semanticsWhen deleting a node or a relationship all properties for that entity will be automatically removed butthe relationships of a node will not be removed

CautionNeo4j enforces a constraint (upon commit) that all relationships must have a validstart node and end node In effect this means that trying to delete a node that still hasrelationships attached to it will throw an exception upon commit It is however possibleto choose in which order to delete the node and the attached relationships as long as norelationships exist when the transaction is committed

The delete semantics can be summarized in the following bullets

bull All properties of a node or relationship will be removed when it is deleted

bull A deleted node can not have any attached relationships when the transaction commits

bull It is possible to acquire a reference to a deleted relationship or node that has not yet beencommitted

bull Any write operation on a node or relationship after it has been deleted (but not yet committed) willthrow an exception

bull After commit trying to acquire a new or work with an old reference to a deleted node or relationshipwill throw an exception

Chapter 4 Cypher Query Language

CautionThis is an experimental feature

A new query language code-named ldquoCypherrdquo has been added to Neo4j It allows for expressive andefficient querying of the graph store without having to write traversers in code

Cypher is designed to be a humane query language suitable for both developers and (importantly wethink) operations professionals who want to make ad-hoc queries on the database Its constructs arebased on English prose and neat iconography which helps to make it (somewhat) self-explanatory

Cypher is inspired by a number of different approaches and builds upon established practices forexpressive querying Most of the keywords like WHERE and ORDER BY are inspired by SQL lthttpenwikipediaorgwikiSQLgt Pattern matching borrows expression approaches from SPARQL lthttpenwikipediaorgwikiSPARQLgt Regular expression matching is implemented using the Scalaprogramming language lthttpwwwscala-langorggt

Cypher is a declarative language It focuses on the clarity of expressing what to retrieve from a graphnot how to do it in contrast to imperative languages like Java and Scala and scripting languages likeGremlin lthttpgremlintinkerpopcomgt (supported via the Section 611 ldquoGremlin Pluginrdquo) and theJRuby Neo4j bindings lthttpneo4jrubyforgeorggt This makes the concern of how to optimizequeries in implementation detail not exposed to the user

The query language is comprised of several distinct parts

Letrsquos see three of them in action

For example here is a query which finds a user called John in an index and then traverses the graphlooking for friends of Johns friends (though not his direct friends) before returning both John and anyfriends-of-friends that are found

Next up we will add filtering to set all four parts in motion

In this next example we take a list of users (by node ID) and traverse the graph looking for thoseother users that have an outgoing friend relationship returning only those followed users who areolder than 18

In Java using the query language looks something like this

db = new ImpermanentGraphDatabase()

Cypher Query Language

engine = new ExecutionEngine( db )

CypherParser parser = new CypherParser()

ExecutionEngine engine = new ExecutionEngine(db)

Query query = parserparse( start n=(0) where 1=1 return n )

ExecutionResult result = engineexecute( query )

assertThat( resultcolumns() hasItem( n ) )

IteratorltNodegt n_column = resultcolumnAs( n )

assertThat( asIterable( n_column ) hasItem(dbgetNodeById(0)) )

assertThat( resulttoString() containsString(Node[0]) )

41 IdentifiersWhen you reference parts of the pattern you do so by naming them

start identifier=(0) return identifier

Identifiers are can be lower or upper case and may contain underscore If other characters are neededyou can use the ` sign Same rules apply to property names

start a=(0) return a`propertywithperiods`

42 StartEvery query describes a pattern and in that pattern one can have multiple bound points A boundpoint is a relationship or a node that form the starting points for a pattern match You can either bindpoints by id or by index lookups

421 Node by idIncluding a node as a start point is done by using parenthesis

start n=(0) return n

The reference node is returned

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

422 Multiple nodes by idMultiple nodes are selected by listing them separated by commas

start n=(1 2 3) return n

The nodes listed in the START statement

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

423 Node by index lookupIf the start point can be found by index lookups it can be done like this (index-name key value)Like this

start n=(nodesnameA) return n

The node indexed with name A is returned

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

424 Node by index queryIf the start point can be found by index queries it can be done like this (index-name query)Thisallows you to write more advanced index queries

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

425 Multiple start pointsSometimes you want to bind multiple start points Just list them separated by commas

start a=(1) b=(2) return ab

Both the A and the B node are returned

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

| Node[1]name-gtA | Node[2]name-gtB |

+-----------------------------------------+

1 rows 1 ms

43 MatchIn the match part of a query the pattern is described The description of the pattern is made up of oneor more paths separated by commas

All parts of the pattern must be directly or indirectly bound to a start point

431 Related nodesThe symbol mdash means related to without regard to type or direction

start n=(3) match (n)--(x) return x

All nodes related to A are returned

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

432 Outgoing relationshipsWhen the direction of a relationship is interesting it is shown by using --gt or lt-- like this

start n=(3) match (n)--gt(x) return x

All nodes that A has outgoing relationships to

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

433 Directed relationships and identifierIf an identifier is needed either for filtering on properties of the relationship or to return therelationship this is how you introduce the identifier

start n=(3) match (n)-[r]-gt() return r

All outgoing relationships from node A

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

434 Match by relationship typeWhen you know the relationship type you want to match on you can specify it by using a colon

start n=(3) match (n)-[BLOCKS]-gt(x) return x

All nodes that are BLOCKed by A

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

435 Match by relationship type and use an identifierIf you both want to introduce an identifier to hold the relationship and specify the relationship typeyou want just add them both like this

start n=(3) match (n)-[rBLOCKS]-gt() return r

All BLOCK relationship going out from A

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

436 Multiple relationshipsRelationships can be expressed by using multiple statements in the form of ()--() or they can bestringed together like this

start a=(3) match (a)-[KNOWS]-gt(b)-[KNOWS]-gt(c) return abc

The three nodes in the path

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

| Node[3]name-gtA | Node[4]name-gtB | Node[2]name-gtE |

+--------------------------------------------------------------+

1 rows 1 ms

437 Complex matchingUsing Cypher you can also express more complex patterns to match on like a diamond shape pattern

start a=(3)

match (a)-[KNOWS]-gt(b)-[KNOWS]-gt(c) (a)-[BLOCKS]-(d)-[KNOWS]-(c)

return abcd

The four nodes in the path

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

+-----------------------------------------------------------------------------------+

1 rows 1 ms

44 WhereIf you need filtering apart from the pattern of the data that you are looking for you can add clauses inthe where part of the query

441 Boolean operationsYou can use the expected boolean operators AND and OR and also the boolean function NOT()

start n=(2 1) where (nage lt 30 and nname = Tobias) or not(nname = Tobias) return n

The node

Result

+-----------------------------------------------+

| Node[2]name-gtAndresage-gt36belt-gtwhite |

| Node[1]name-gtTobiasage-gt25 |

+-----------------------------------------------+

2 rows 1 ms

442 Filter on node propertyTo filter on a property write your clause after the WHERE keyword

start n=(2 1) where nage lt 30 return n

The node

Result

+---------------------------------+

1 rows 4 ms

443 Regular expressionsYou can match on regular expressions by using =~ regexp like this

start n=(2 1) where nname =~ Tob return n

The node named Tobias

Result

+---------------------------------+

1 rows 0 ms

444 Filtering on relationship typeYou can put the exact relationship type in the MATCH pattern but sometimes you want to be able todo more advanced filtering on the type You can use the special property TYPE to compare the type

with something else In this example the query does a regular expression comparison with the nameof the relationship type

start n=(2) match (n)-[r]-gt() where r~TYPE =~ K return r

The relationship that has a type whose name starts with K

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

445 Property existsTo only include nodesrelationships that have a property just write out the identifier and the propertyyou expect it to have

start n=(2 1) where nbelt return n

The node named Andres

Result

+-----------------------------------------------+

1 rows 1 ms

45 ReturnIn the return part of your query you define which parts of the pattern you are interested in It can benodes relationships or properties on these

451 Return nodesTo return a node list it in the return statemenet

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

452 Return relationshipsTo return a relationship just include it in the return list

start n=(1) match (n)-[rKNOWS]-gt(c) return r

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

453 Relationship typeWhen you want to output the relationship type and not the whole relationship you can use ~TYPE

start n=(1) match (n)-[r]-gt() return r~TYPE

The relationship type of r

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

454 Return propertyTo return a property use the dot separator like this

start n=(1) return nname

The the value of the property name

Result

+--------+

| nname |

+--------+

1 rows 1 ms

455 Identifier with uncommon charactersTo introduce a placeholder that is made up of characters that are outside of the english alphabet youcan use the ` to enclose the identifier like this

start `This isnt a common identifier`=(1)

return `This isnt a common identifier``ltlt__gtgt`

Result

+-------------------------------------------+

| This isnt a common identifierltlt__gtgt |

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

456 Optional propertiesIf a property might or might not be there you can select it optionally by adding a questionmark to theidentifier like this

start n=(1 2) return nage

The age when the node has that property or null if the property is not there

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

46 AggregationTo calculate aggregated data Cypher offers aggregation much like SQLrsquos GROUP BY If anyaggregation functions are found in the RETURN statement all the columns without aggregatingfunctions are used as the grouping key

461 COUNTCOUNT is used to count the number of rows COUNT can be used in two forms - COUNT() whichjust counts the number of matching rows and COUNT(ltidentifiergt) which counts the number ofnon-null values in ltidentifiergt

462 Count nodesTo count the number of nodes for example the number of nodes connected to one node you can usecount()

start n=(2) match (n)--gt(x) return n count()

The start node and the count of related nodes

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

| Node[2]name-gtAproperty-gt13 | 3 |

+--------------------------------------------+

1 rows 2 ms

463 Count entitiesInstead of counting the number of results with count() it might be more expressive to include thename of the identifier you care about

start n=(2) match (n)--gt(x) return count(x)

The number of connected nodes from the start node

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

464 Count non null valuesYou can count the non-null values by using count(ltidentifiergt)

start n=(2341) return count(nproperty)

The count of related nodes

Result

+-------------------+

| count(nproperty) |

+-------------------+

1 rows 1 ms

465 SUMThe SUM aggregation function simply sums all the numeric values it encounters Null values aresilently dropped This is an example of how you can use SUM

start n=(234) return sum(nproperty)

The sum of all the values in the property property

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

466 AVGAVG calculates the average of a numeric column

start n=(234) return avg(nproperty)

The average of all the values in the property property

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

467 MAXMAX find the largets value in a numeric column

start n=(234) return max(nproperty)

The largest of all the values in the property property

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

468 MINMIN takes a numeric property as input and returns the smallest value in that column

start n=(234) return min(nproperty)

The smallest of all the values in the property property

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

47 Order byTo sort the output use the Order by clause Note that you can not sort on nodes or relationships juston properties on these

471 Order nodes by propertyORDER BY is used to sort the output

start n=(312) return n order by nname

The nodes sorted by their name

Result

+----------------------------------------+

| Node[1]name-gtAage-gt34length-gt170 |

| Node[2]name-gtBage-gt34 |

| Node[3]name-gtCage-gt32length-gt185 |

+----------------------------------------+

3 rows 1 ms

472 Order nodes by multiple propertiesYou can order by multiple properties by stating each identifier in the ORDER BY statement Cypherwill sort the result by the first identifier listed and for equals values go to the next property in theorder by and so on

start n=(312) return n order by nage nname

The nodes sorted first by their age and then by their name

Result

+----------------------------------------+

3 rows 1 ms

473 Order nodes in descending orderBy adding DESC[ENDING] after the identifier to sort on the sort will be done in reverse order

start n=(312) return n order by nname DESC

The nodes sorted by their name reversely

Result

+----------------------------------------+

3 rows 1 ms

474 Ordering nullWhen sorting the result set null will always come at the end of the result set for ascending sortingand first when doing descending sort

start n=(312) return nlength n order by nlength

The nodes sorted by the length property with a node without that property last

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

| 170 | Node[1]name-gtAage-gt34length-gt170 |

| 185 | Node[3]name-gtCage-gt32length-gt185 |

| ltnullgt | Node[2]name-gtBage-gt34 |

+---------------------------------------------------+

3 rows 1 ms

48 SkipSkip enables the return of only subsets of the total result By using skip the result set will trimmedfrom the top Please note that no guarantees are made on the order of the result unless the queryspecies the order by clause

481 Skip first threeTo return a subset of the result starting from third result use this syntax

start n=(3 4 5 1 2) return n order by nname skip 3

The first three nodes are skipped and only the last two are returned

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

482 Return middle twoTo return a subset of the result starting from somewhere in the middle use this syntax

start n=(3 4 5 1 2) return n order by nname skip 1 limit 2

Two nodes from the middle are returned

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

49 LimitLimit enables the return of only subsets of the total result

491 Return first partTo return a subset of the result starting from the top use this syntax

start n=(3 4 5 1 2) return n limit 3

The top three items are returned

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Chapter 5 Neo4j Server

Neo4j Server

51 Server InstallationNeo4j can be installed as a server running either as a headless application or system service

1 Download the latest release from httpneo4jorgdownload

bull select the appropriate version for your platform

2 Extract the contents of the archive

bull refer to the top-level extracted directory as NEO4J-HOME

3 Use the scripts in the bin directory

bull for LinuxMacOS run $NEO4J_HOMEbinneo4j start

bull for Windows double-click on NEO4J_HOMEbinNeo4jbat

4 Refer to the packaged information in the doc directory for details

511 As a Windows serviceWith administrative rights Neo4j can be installed as a Windows service

1 Click Start ndashgt All Programs ndashgt Accessories

2 Right click Command Prompt ndashgt Run as Administrator

3 Provide authorization andor the Administrator password

4 Navigate to NEO4J_HOME

5 Run binNeo4jbat install

To uninstall run binNeo4jbat remove as Administrator

To query the status of the service run binNeo4jbat query

To startstop the service from the command prompt run binNeo4jbat +action+

512 Linux ServiceNeo4j can participate in the normal system startup and shutdown process The following procedureshould work on most popular Linux distributions

1 cd $NEO4J_HOME

2 sudo binneo4j install

bull if asked enter your password to gain super-user privileges

3 service neo4j-server status

bull should indicate that the server is not running

4 service neo4j-server start

bull will start the server

During installation you will be given the option to select the user Neo4j will run as You will be asked to supply a username (defaulting to `neo4j`) and if that user is not present on the system it will be created as a system account and the `$NEO4J_HOMEdata` directory will be `chown`ed to that user

You are encouraged to create a dedicated user for running the service and for that reason it is suggested that you unpack the distribution package under `opt` or your site specific optional packages directory

Finally note that if you chose to create a new user account on uninstall you will be prompted to remove it from the system

513 Macintosh ServiceNeo4j can be installed as a Mac launchd job

1 cd $NEO4J_HOME

Neo4j Server

3 launchctl load ~LibraryLaunchAgentswrapperneo4j-serverplist

bull needed to tell launchd about the job

4 launchctl list | grep neo

bull should reveal the launchd wrapperneo4j-server job for running the Neo4j Server

5 launchctl start wrapperneo4j-server

bull to start the Neo4j Server under launchd control

6 binneo4j status

bull should indicate that the server is running

514 Multiple Server instances on one machineNeo4j can be set up to run as several instances on one machine providing for instance severaldatabases for development To configure install two instances of the Neo4j Server in two differentdirectories Before running the Windows install or startup change in confneo4j-wrapperconf

Name of the service for the first instance

wrappername=neo4j_1

and for the second instance

Name of the service for the second instance

wrappername=neo4j_2

in order not to get name clashes installing and starting the instances as services

Also the port numbers for the web administration and the servers should be changed to non-clashingvalues in confneo4j-serverproperties

Server 1 (port 7474)

orgneo4jserverwebserverport=7474

orgneo4jserverwebadmindatauri=httplocalhost7474dbdata

orgneo4jserverwebadminmanagementuri=httplocalhost7474dbmanage

Neo4j Server

52 Server Configuration

Quick info

bull The serverrsquos primary configuration file is found under confneo4j-serverproperties

bull The conflog4jproperties file contains the default server logging configuration

bull Low-level performance tuning parameters are found in confneo4jproperties

bull Configuraion of the deamonizing wrapper are found in confneo4j-wrapperproperties

521 Important server configurations parametersThe main configuration file for the server can be found at confneo4j-serverproperties This filecontains several important settings and although the defaults are sensible administrators might chooseto make changes (especially to the port settings)

Set the location on disk of the database directory like this

orgneo4jserverdatabaselocation=datagraphdb

NoteOn Windows systems absolute locations including drive letters need to read cdatadb

Specify the HTTP server port supporting data administrative and UI access

Set the location of the round-robin database directory which gathers metrics on the running serverinstance

orgneo4jserverwebadminrrdblocation=datagraphdbrrd

Set the URI path for the REST data API through which the database is accessed For non-local accessuse the full URI of your server eg httpexampleorg7575database For local access use a relativeURI eg dbdata

orgneo4jserverwebadmindatauri=dbdata

Setting the management URI for the administration API that the Webadmin tool uses For non-localaccess use the full URI of your server eg httpexampleorg7575databasemanagement For localaccess use a relative URI eg dbmanage

orgneo4jserverwebadminmanagementuri=dbmanage

If you plan to connect to the Webadmin from other than localhost put in the external hostname ofyour server instead of localhost eg httpmyhost7474dbmanage Force the server to use IPv4network addresses in confneo4j-wrapperconf under the section Java Additional Parameters add anew paramter

wrapperjavaadditional3=-DjavanetpreferIPv4Stack=true

Low-level performance tuning parameters can be explicitly set by referring to the following property

orgneo4jserverdbtuningproperties=neo4jproperties

If this property isnrsquot set the server will look for a file called neo4jproperties in the same directory asthe neo4j-serverproperties file

Neo4j Server

If this property isnrsquot set and there is no neo4jproperties file in the default configuration directorythen the server will log a warning Subsequently at runtime the database engine will attempt tune itselfbased on the prevailing conditions

522 Neo4j Database performance configurationThe fine-tuning of the low-level Neo4j graph database engine is specified in a separate properties fileconfneo4jproperties

The graph database engine has a range of performance tuning options which are enumerated inSection 57 ldquoTuning the server performancerdquo Note that other factors than Neo4j tuning shouldbe considered when performance tuning a server including general server load memory and filecontention and even garbage collection penalties on the JVM though such considerations are beyondthe scope of this configuration document

523 Logging configurationThe logging framework in use by the Neo4j server is javautillogging lthttpdownloadoraclecomjavase6docstechnotesguidesloggingoverviewhtmlgt and isconfigured in confloggingproperties

By default it is setup to print INFO level messages both on screen and in a rolling file in datalogMost deployments will choose to use their own configuration here to meet local standards Duringdevelopment much useful information can be found in the logs so some form of logging to disk iswell worth keeping On the other hand if you want to completely silence the console output set

javautilloggingConsoleHandlerlevel=OFF

Apart from log statements originating from the Neo4j server other libraries report their messagesthrough various frameworks

Zookeeper is hardwired to use the log4j logging framework The bundled conflog4jproperties appliesfor this use only and uses a rolling appender and outputs logs by default to the datalog directory

524 Other configuration options

Enabling logging from the garbage collectorTo get garbage collection logging output you have to pass the corresponding option to the server JVMexecutable by setting in confneo4j-wrapperconf the value

wrapperjavaadditional3=-Xloggcdatalogneo4j-gclog

This line is already present and needs uncommenting Note also that logging is not directed toconsole You will find the logging statements in datalogne4j-gclog or whatever directory you set atthe option

Neo4j Server

53 Setup for remote debuggingIn order to configure the Neo4j server for remote debugging sessions the Java debugging parametersneed to be passed to the Java process through the configuration They live in the confneo4j-wrapperproperties file

In order to specify the parameters add a line for the additional Java arguments like this

Java Additional Parameters

wrapperjavaadditional1=-Dorgneo4jserverproperties=confneo4j-serverproperties

wrapperjavaadditional2=-Dlog4jconfiguration=fileconflog4jproperties

wrapperjavaadditional3=-agentlibjdwp=transport=dt_socketserver=ysuspend=naddress=5005 -Xdebug-Xnoagent-Djavacompiler=NONE-Xrunjdwptransport=dt_socketserver=ysuspend=naddress=5005

This configuration will start a Neo4j server ready for remote debugging attachement at localhost andport 5005 Use these parameters to attach to the process from Eclipse IntelliJ or your remote debuggerof choice after starting the server

Neo4j Server

54 Starting the Neo4j server in high availability mode

NoteThe High Availability features are only available in the Neo4j Enterprise Edition

To run the Neo4j server in high availability mode there are two things you need to do You have toconfigure the server to start up the database in high availability mode and you have to configure theNeo4j database for operating in high availability mode

Instructing the server to start the database in high availability mode is as easy as settingthe orgneo4jserverdatabasemode property in the server properties file (confneo-serverproperties) to ha The default value for this parameter is single which will start the databasein standalone mode without participating in a cluster still giving you Online Backup

Configuring the Neo4j database for operating in high availability mode requires specifying a fewproperties in confneo4jproperties First you need to specify hamachine_id this is a positive integerid that uniquely identifies this server in the cluster

Example hamachine_id = 1

Then you have to specify hazoo_keeper_servers this is a comma separated list of hosts and portsfor communicating with each member of the Neo4j Coordinator cluster

For example hazoo_keeper_servers = neo4j-manager-012180neo4j-manager-022180neo4j-manager-032180

You can also optionally configure the hacluster_name This is the name of the cluster thisinstance is supposed to join Accepted characters are alphabetical numerical dot dash andunderscore This configuration is useful if you have multiple Neo4j HA clusters managed by the sameCoordinator cluster

Example hacluster_name = my_neo4j_ha_cluster

541 Starting a Neo4j CoordinatorA Neo4j Coordinator cluster provides the Neo4j HA Data cluster with reliable coordination oflifecycle activities like electing the master Neo4j Server includes everything needed for running aNeo4j Coordinator

Configuration of a Coordinator is specified in these files

bull confcoordcfg - coordinator operational settings

bull datacoordinatormyid - unqiue identification of the coordinator

Once a Neo4j Coordinator instance has been configured you can use the binneo4j-coordinatorcommand to start the Neo4j Coordinator server on all desired servers with the same configuration justchanging the datacoordinatormyid to unique numbers You can check that the coordinator is up byrunning jconsole attaching to the JVM and check for orgapachezookeeper MBeans

Neo4j Server

Figure 51 Neo4j Coordinator MBeans View

542 Starting the Neo4j ServerOnce the desired neo4j Coordinators are up and running you are ready to start your Neo4j HAinstance using binneo4j start The details of the HA logs are available in the messageslog of thegraph database data directory normally datagraphdbmesageslog You should see an entry like thisone

Tue Apr 12 092558 CEST 2011 MasterServer communication server started and bound to 6361

Tue Apr 12 092558 CEST 2011 Started as master

Tue Apr 12 092558 CEST 2011 master-rebound set to 1

Neo4j Server

55 Using the server with an embedded databaseEven if you are using the Neo4j Java API directly for instance via EmbeddedGraphDatabase orHighlyAvailableGraphDatabase you can still use the features the server provides

The neo4j server exposes a class called WrappingNeoServerBootstrapper which is capable of startinga neo4j server in the same process as your application using an AbstractGraphDatabase instance youprovide

This gives your application among other things the REST API statistics gathering and the webadministration interface that comes with the server

Usage example

WrappingNeoServerBootstrapper srv = new WrappingNeoServerBootstrapper( myDb )

srvstart()

Server is now running in background threads

srvstop()

551 Providing custom configurationYou can modify the server settings programmatically and within reason the same settings areavailable to you here as those outlined in the Server Configuration chapter

The settings that are not available (or rather that are ignored) are those that concern the underlyingdatabase such as database location and database configuration path

Custom config example

EmbeddedServerConfigurator config = new EmbeddedServerConfigurator( myDb )

configconfiguration()

setProperty( ConfiguratorWEBSERVER_PORT_PROPERTY_KEY 7575 )

WrappingNeoServerBootstrapper srv = new WrappingNeoServerBootstrapper( myDb config )

srvstart()

Neo4j Server

56 Server Plugins

Quick info

bull The serverrsquos functionality can be extended by adding plugins Plugins are user-specifiedcode which extend the capabilities of the database nodes or relationships The neo4j serverwill then advertise the plugin functionality within representations as clients interact viaHTTP

Plugins provide an easy way to extend the Neo4j REST API with new functionality without the needto invent your own API Think of plugins as server-side scripts that can add functions for retrievingand manipulating nodes relationships paths properties or indices

TipIf you want to have full control over your API and are willing to put in the effort andunderstand the risks then Neo4j server also provides hooks for unmanaged extensionsbased on JAX-RS

The needed classes reside in the orgneo4jserver-api lthttpsearchmavenorgsearch|gav|1|g3A22orgneo4j2220AND20a3A22server-api22gt jar file See the linked page fordownloads and instructions on how to include it using dependency management For Maven projectsadd the Server API dependencies in your pomxml like this

ltdependencygt

ltartifactIdgtserver-apiltartifactIdgt

ltdependencygt

Where $neo4j-version is the intended version

To create a plugin your code must inherit from the ServerPlugin lthttpcomponentsneo4jorgserver-api14M06apidocsorgneo4jserverpluginsServerPluginhtmlgt class Your plugin should also

bull ensure that it can produce an (Iterable of) Node Relationship or Path

bull specify parameters

bull specify a point of extension and of course

bull contain the application logic

bull make sure that the discovery point type in the PluginTarget and the Source parameter are ofthe same type

An example of a plugin which augments the database (as opposed to nodes or relationships) follows

Get all nodes or relationships plugin

Description( An extension to the Neo4j Server for getting all nodes or relationships )

public class GetAll extends ServerPlugin

Name( get_all_nodes )

Description( Get all nodes from the Neo4j graph database )

PluginTarget( GraphDatabaseServiceclass )

public IterableltNodegt getAllNodes( Source GraphDatabaseService graphDb )

return graphDbgetAllNodes()

Neo4j Server

Description( Get all relationships from the Neo4j graph database )

public IterableltRelationshipgt getAllRelationships( Source GraphDatabaseService graphDb )

return new NestingIterableltRelationship Nodegt( graphDbgetAllNodes() )

Override

protected IteratorltRelationshipgt createNestedIterator( Node item )

return itemgetRelationships( DirectionOUTGOING )iterator()

Find the shortest path between two nodes plugin

public class ShortestPath extends ServerPlugin

Description( Find the shortest path between two nodes )

PluginTarget( Nodeclass )

public IterableltPathgt shortestPath(

Source Node source

Description( The node to find the shortest path to )

Parameter( name = target ) Node target

Description( The relationship types to follow when searching for the shortest path(s) +

Order is insignificant if omitted all types are followed )

Parameter( name = types optional = true ) String[] types

Description( The maximum path length to search for default value (if omitted) is 4 )

Parameter( name = depth optional = true ) Integer depth )

Expander expander

if ( types == null )

expander = TraversalexpanderForAllTypes()

expander = TraversalemptyExpander()

for ( int i = 0 i lt typeslength i++ )

expander = expanderadd( DynamicRelationshipTypewithName( types[i] ) )

PathFinderltPathgt shortestPath = GraphAlgoFactoryshortestPath(

expander depth == null 4 depthintValue() )

return shortestPathfindAllPaths( source target )

To deploy the code simply compile it into a jar file and place it onto the server classpath (whichby convention is the plugins directory under the Neo4j server home directory) The jar file mustinclude the file META-INFservicesorgneo4jserverpluginsServerPlugin with the fully qualifiedname of the implementation class In this case wersquod have only a single entry in our config file thoughmultiple entries are allowed each on a separate line

orgneo4jserverexamplesGetAll

Any other plugins in the same jar file must be listed here

The code above makes an extension visible in the database representation (via the PluginTargetannotation) whenever it is served from the Neo4j Server Simply changing the PluginTargetparameter to Nodeclass or Relationshipclass allows us to target those parts of the data model

Neo4j Server

should we wish The functionality extensions provided by the plugin are automatically advertisedin representations on the wire For example clients can discover the extension implemented by theabove plugin easily by examining the representations they receive as responses from the server egby performing a GET on the default database URI

curl -v httplocalhost7474dbdata

The response to the GET request will contain (by default) a JSON container that itself contains acontainer called extensions where the available plugins are listed In the following case we onlyhave the GetAll plugin registered with the server so only its extension functionality is availableExtension names will be automatically assigned based on method names if not specifically specifiedusing the Name annotation

extensions-info httplocalhost7474dbdataext

node httplocalhost7474dbdatanode

node_index httplocalhost7474dbdataindexnode

relationship_index httplocalhost7474dbdataindexrelationship

reference_node httplocalhost7474dbdatanode0

extensions_info httplocalhost7474dbdataext

extensions

GetAll

get_all_nodes httplocalhost7474dbdataextGetAllgraphdbget_all_nodes

get_all_relationships httplocalhost7474dbdataextGetAllgraphdbgetAllRelationships

Performing a GET on one of the two extension URIs gives back the meta information about theservice

curl httplocalhost7474dbdataextGetAllgraphdbget_all_nodes

extends graphdb

description Get all nodes from the Neo4j graph database

name get_all_nodes

parameters [ ]

To use it just POST to this URL with parameters as specified in the description and encoded asJSON data content Fex for calling the shortest path extension (URI gotten from a GET to httplocalhost7474dbdatanode123)

curl -X POST httplocalhost7474dbdataextGetAllnode123shortestPath -H Content-Type applicationjson -d targethttplocalhost7474dbdatanode456ampdepth=5

If everything is OK a response code 200 and a list of zero or more items will be returned If nothing isreturned (null returned from extension) an empty result and response code 204 will be returned If theextension throws an exception response code 500 and a detailed error message is returned

Extensions that do any kind of write operation will have to manage their own transactions ietransactions arenrsquot managed automatically

Through this model any plugin can naturally fit into the general hypermedia scheme that Neo4jespouses - meaning that clients can still take advantage of abstractions like Nodes Relationshipsand Paths with a straightforward upgrade path as servers are enriched with plugins (old clients donrsquotbreak)

Neo4j Server

57 Tuning the server performanceAt the heart of the Neo4j server is a regular Neo4j storage engine instance That engine can be tunedin the same way as the other embedded configurations using the same file format The only differenceis that the server must be told where to find the fine-tuning configuration

Quick info

bull The neo4jproperties file is a standard configuration file that databases load in order to tunetheir memory use and caching strategies

bull See Section 21 ldquoCaches in Neo4jrdquo for more information

571 Specifying Neo4j tuning propertiesThe confneo4j-serverproperties file in the server distribution is the main configuration filefor the server In this file we can specify a second properties file that contains the database tuningsettings (that is the neo4jproperties file) This is done by setting a single property to point to avalid neo4jproperties file

orgneo4jserverdbtuningproperties=neo4jproperties file

On restarting the server the tuning enhancements specified in the neo4jproperties file will beloaded and configured into the underlying database engine

572 Specifying JVM tuning propertiesTuning the standalone server is achieved by editing the neo4j-wrapperconf file in the confdirectory of NEO4J_HOME

Edit the following properties

Table 51 neo4j-wrapperconf JVM tuning properties

Property Name Meaning

wrapper java initmemory initial heap size (in MB)

wrapper java maxmemory maximum heap size (in MB)

wrapper java additional N additional literal JVM parameter where N is anumber for each

For more information on the tuning properties see Section 22 ldquoJVM Settingsrdquo

Neo4j Server

58 Unmanaged Extensions

Quick info

bull Danger Men at Work The unmanaged extensions are a way of deploying arbitrary JAX-RS code into the Neo4j server

bull The unmanaged extensions are exactly that unmanaged If you drop poorly tested code intothe server itrsquos highly likely yoursquoll degrade its performance so be careful

Some projects want extremely fine control over their server-side code For this wersquove introduced anunmanaged extension API

WarningThis is a sharp tool allowing users to deploy arbitrary JAX-RS lthttpenwikipediaorgwikiJAX-RSgt classes to the server and so you should be careful when thinking aboutusing this In particular you should understand that itrsquos easy to consume lots of heap spaceon the server and hinder performance if yoursquore not careful

Still if you understand the disclaimer then you load your JAX-RS classes into the Neo4j serversimply by adding adding a Context annotation to your code compiling against the JAX-RS jar andany Neo4j jars yoursquore making use of Then add your classes to the runtime classpath (just drop it inthe lib directory of the Neo4j server) In return you get access to the hosted environment of the Neo4jserver like logging through the orgneo4jserverloggingLogger

In your code you get access to the underlying GraphDatabaseService through the Contextannotation like so

public MyCoolService(Context GraphDatabaseService database)

Have fun here but be safe

Remember the unmanaged API is a very sharp tool Itrsquos all to easy to compromise the server bydeploying code this way so think first and see if you canrsquot use the managed extensions in preferenceHowever a number of context parameters can be automatically provided for you like the reference tothe database

In order to specify the mount point of your extension a full class looks like this

Unmanaged extension example

Path( helloworld )

public class HelloWorldResource

private final GraphDatabaseService database

public HelloWorldResource( Context GraphDatabaseService database )

thisdatabase = database

Produces( MediaTypeTEXT_PLAIN )

Path( nodeId )

public Response hello( PathParam( nodeId ) long nodeId )

Neo4j Server

Do stuff with the database

return Responsestatus( StatusOK )entity(

( Hello World nodeId= + nodeId )getBytes() )build()

Build this code and place the resulting jar file (and any custom dependencies) into the$NEO4J_SERVER_HOMEplugins directory and include this class in the neo4j-serverpropertiesfile like so

Comma separated list of JAXRS packages containing JAXRS Resource one package name for each mountpoint

orgneo4jserverthirdparty_jaxrs_classes=orgneo4jexamplesserverunmanaged=examplesunmanaged

Which binds the hello method to respond to GET requests at the URI httpneo4j_serverneo4j_portexamplesunmanagedhelloworldnodeId

curl httplocalhost7474examplesunmanagedhelloworld123

which results in

Hello World nodeId=123

Chapter 6 REST API

The Neo4j REST API is designed with discoverability in mind so that you can start with a GET onthe Section 61 ldquoService rootrdquo and from there discover URIs to perform other requests The examplesbelow uses URIs in the examples they are subject to change in the future so for future-proofnessdiscover URIs where possible instead of relying on the current layout The default representation isjson lthttpwwwjsonorggt both for responses and for data sent with POSTPUT requests

Below follows a listing of ways to interact with the REST API You can also see a (at runtime)generated description of the API be pointing your browser to the (exact URI may vary) httplocalhost7474dbdataapplicationwadl

To interact with the JSON interface you must explicitly set the request header Acceptapplicationjson for those requests that responds with data You should also set the header Content-Typeapplicationjson if your request sends data for example when yoursquore creating a relationshipThe examples include the relevant request and response headers

REST API

61 Service root

611 Get service rootThe service root is your starting point to discover the REST API

Example request

bull GET httplocalhost7474dbdata

bull Accept applicationjson

Example response

bull 200 OK

bull Content-Type applicationjson

relationship_types httplocalhost7474dbdatarelationshiptypes

extensions

FunctionalTestPlugin

methodWithArray httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithArray

methodWithIntArray httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithIntArray

methodWithIntParam httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithIntParam

reference_node_uri httplocalhost7474dbdataextFunctionalTestPlugingraphdbreference_node_uri

methodWithSet httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithSet

methodWithOptionalArray httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithOptionalArray

methodWithListAndInt httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithListAndInt

methodWithList httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithList

methodWithAllParams httplocalhost7474dbdataextFunctionalTestPlugingraphdbmethodWithAllParams

REST API

62 Nodes

621 Create nodeExample request

bull POST httplocalhost7474dbdatanode

Example response

bull 201 Created

bull Location httplocalhost7474dbdatanode1

outgoing_relationships httplocalhost7474dbdatanode1relationshipsout

traverse httplocalhost7474dbdatanode1traversereturnType

all_typed_relationships httplocalhost7474dbdatanode1relationshipsall-list|amp|types

property httplocalhost7474dbdatanode1propertieskey

self httplocalhost7474dbdatanode1

outgoing_typed_relationships httplocalhost7474dbdatanode1relationshipsout-list|amp|types

properties httplocalhost7474dbdatanode1properties

incoming_relationships httplocalhost7474dbdatanode1relationshipsin

extensions

connected_nodes httplocalhost7474dbdataextFunctionalTestPluginnode1connected_nodes

pathToReference httplocalhost7474dbdataextFunctionalTestPluginnode1pathToReference

getThisNodeOrById httplocalhost7474dbdataextFunctionalTestPluginnode1getThisNodeOrById

createRelationships httplocalhost7474dbdataextFunctionalTestPluginnode1createRelationships

getRelationshipsBetween httplocalhost7474dbdataextFunctionalTestPluginnode1getRelationshipsBetween

GraphCloner

clonedSubgraph httplocalhost7474dbdataextGraphClonernode1clonedSubgraph

create_relationship httplocalhost7474dbdatanode1relationships

paged_traverse httplocalhost7474dbdatanode1pagedtraversereturnTypepageSizeleaseTime

all_relationships httplocalhost7474dbdatanode1relationshipsall

incoming_typed_relationships httplocalhost7474dbdatanode1relationshipsin-list|amp|types

622 Create node with propertiesExample request

foo bar

Example response

bull 201 Created

bull Content-Length 1819

REST API

foo bar

extensions

GraphCloner

623 Get nodeNote that the response contains URItemplates for the available operations for getting properties andrelationships

Example request

bull GET httplocalhost7474dbdatanode1

Example response

bull 200 OK

extensions

REST API

GraphCloner

624 Get non-existent nodeExample request

Example response

bull 404 Not Found

message Cannot find node with id [600000] in database

exception orgneo4jserverrestwebNodeNotFoundException Cannot find node with id [600000] in database

stacktrace [ orgneo4jserverrestwebDatabaseActionsnode(DatabaseActionsjava98) orgneo4jserverrestwebDatabaseActionsgetNode(DatabaseActionsjava194) orgneo4jserverrestwebRestfulGraphDatabasegetNode(RestfulGraphDatabasejava185) sunreflectNativeMethodAccessorImplinvoke0(Native Method) sunreflectNativeMethodAccessorImplinvoke(NativeMethodAccessorImpljava39) sunreflectDelegatingMethodAccessorImplinvoke(DelegatingMethodAccessorImpljava25) javalangreflectMethodinvoke(Methodjava597) comsunjerseyserverimplmodelmethoddispatchAbstractResourceMethodDispatchProvider$ResponseOutInvoker_dispatch(AbstractResourceMethodDispatchProviderjava184) comsunjerseyserverimplmodelmethoddispatchResourceJavaMethodDispatcherdispatch(ResourceJavaMethodDispatcherjava67) comsunjerseyserverimplurirulesHttpMethodRuleaccept(HttpMethodRulejava276) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesResourceClassRuleaccept(ResourceClassRulejava83) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesRootResourceClassesRuleaccept(RootResourceClassesRulejava71) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1171) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1103) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1053) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1043) comsunjerseyspicontainerservletWebComponentservice(WebComponentjava406) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava477) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava662) javaxservlethttpHttpServletservice(HttpServletjava820) orgmortbayjettyservletServletHolderhandle(ServletHolderjava511) orgmortbayjettyservletServletHandlerhandle(ServletHandlerjava390) orgmortbayjettyservletSessionHandlerhandle(SessionHandlerjava182) orgmortbayjettyhandlerContextHandlerhandle(ContextHandlerjava765) orgmortbayjettyhandlerHandlerCollectionhandle(HandlerCollectionjava114) orgmortbayjettyhandlerHandlerWrapperhandle(HandlerWrapperjava152) orgmortbayjettyServerhandle(Serverjava326) orgmortbayjettyHttpConnectionhandleRequest(HttpConnectionjava542) orgmortbayjettyHttpConnection$RequestHandlerheaderComplete(HttpConnectionjava926) orgmortbayjettyHttpParserparseNext(HttpParserjava549) orgmortbayjettyHttpParserparseAvailable(HttpParserjava212) orgmortbayjettyHttpConnectionhandle(HttpConnectionjava404) orgmortbayjettybioSocketConnector$Connectionrun(SocketConnectorjava228) orgmortbaythreadQueuedThreadPool$PoolThreadrun(QueuedThreadPooljava582) ]

625 Delete nodeExample request

bull DELETE httplocalhost7474dbdatanode9

Example response

bull 204 No Content

626 Nodes with relationships can not be deletedThe relationships on a node has to be deleted before the node can be deleted

Example request

Example response

bull 409 Conflict

REST API

message The node with id 10 cannot be deleted Check that the node is orphaned before deletion

exception orgneo4jserverrestwebOperationFailureException The node with id 10 cannot be deleted Check that the node is orphaned before deletion

stacktrace [ orgneo4jserverrestwebDatabaseActionsdeleteNode(DatabaseActionsjava214) orgneo4jserverrestwebRestfulGraphDatabasedeleteNode(RestfulGraphDatabasejava199) sunreflectNativeMethodAccessorImplinvoke0(Native Method) sunreflectNativeMethodAccessorImplinvoke(NativeMethodAccessorImpljava39) sunreflectDelegatingMethodAccessorImplinvoke(DelegatingMethodAccessorImpljava25) javalangreflectMethodinvoke(Methodjava597) comsunjerseyserverimplmodelmethoddispatchAbstractResourceMethodDispatchProvider$ResponseOutInvoker_dispatch(AbstractResourceMethodDispatchProviderjava184) comsunjerseyserverimplmodelmethoddispatchResourceJavaMethodDispatcherdispatch(ResourceJavaMethodDispatcherjava67) comsunjerseyserverimplurirulesHttpMethodRuleaccept(HttpMethodRulejava276) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesResourceClassRuleaccept(ResourceClassRulejava83) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesRootResourceClassesRuleaccept(RootResourceClassesRulejava71) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1171) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1103) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1053) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1043) comsunjerseyspicontainerservletWebComponentservice(WebComponentjava406) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava477) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava662) javaxservlethttpHttpServletservice(HttpServletjava820) orgmortbayjettyservletServletHolderhandle(ServletHolderjava511) orgmortbayjettyservletServletHandlerhandle(ServletHandlerjava390) orgmortbayjettyservletSessionHandlerhandle(SessionHandlerjava182) orgmortbayjettyhandlerContextHandlerhandle(ContextHandlerjava765) orgmortbayjettyhandlerHandlerCollectionhandle(HandlerCollectionjava114) orgmortbayjettyhandlerHandlerWrapperhandle(HandlerWrapperjava152) orgmortbayjettyServerhandle(Serverjava326) orgmortbayjettyHttpConnectionhandleRequest(HttpConnectionjava542) orgmortbayjettyHttpConnection$RequestHandlerheaderComplete(HttpConnectionjava926) orgmortbayjettyHttpParserparseNext(HttpParserjava549) orgmortbayjettyHttpParserparseAvailable(HttpParserjava212) orgmortbayjettyHttpConnectionhandle(HttpConnectionjava404) orgmortbayjettybioSocketConnector$Connectionrun(SocketConnectorjava228) orgmortbaythreadQueuedThreadPool$PoolThreadrun(QueuedThreadPooljava582) ]

REST API

63 RelationshipsThe general pattern to get relationships is

GET httplocalhost7474dbdatanode123relationshipsdir-list|amp|types

Where dir is one of all in out and types is an ampersand-separated list of types See the examplesbelow for more information

631 Create relationshipExample request

bull POST httplocalhost7474dbdatanode3relationships

to httplocalhost7474dbdatanode4 type LOVES

Example response

bull 201 Created

bull Location httplocalhost7474dbdatarelationship2

start httplocalhost7474dbdatanode3

self httplocalhost7474dbdatarelationship2

property httplocalhost7474dbdatarelationship2propertieskey

properties httplocalhost7474dbdatarelationship2properties

type LOVES

extensions

methodOnRelationship httplocalhost7474dbdataextFunctionalTestPluginrelationship2methodOnRelationship

end httplocalhost7474dbdatanode4

632 Get all relationshipsExample request

bull GET httplocalhost7474dbdatanode6relationshipsall

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

633 Get incoming relationshipsExample request

bull GET httplocalhost7474dbdatanode11relationshipsin

Example response

bull 200 OK

type LIKES

extensions

REST API

634 Get outgoing relationshipsExample request

bull GET httplocalhost7474dbdatanode16relationshipsout

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

635 Get typed relationshipsNote that the amp needs to be escaped for example when using cURL lthttpcurlhaxxsegt from theterminal

Example request

bull GET httplocalhost7474dbdatanode21relationshipsallLIKESampHATES

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

636 Get relationships on a node without relationshipsExample request

Example response

bull 200 OK

REST API

64 Relationship types

641 Get relationship typesExample request

bull GET httplocalhost7474dbdatarelationshiptypes

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

651 Set property on nodeExample request

bull PUT httplocalhost7474dbdatanode5propertiesfoo

Example response

bull 204 No Content

652 Update node propertiesExample request

bull PUT httplocalhost7474dbdatanode1properties

jim tobias

Example response

bull 204 No Content

653 Get properties for nodeExample request

bull GET httplocalhost7474dbdatanode5properties

Example response

bull 200 OK

foo bar

654 Get properties for node (empty result)If there are no properties there will be an HTTP 204 response

Example request

REST API

Example response

bull 204 No Content

655 Property values can not be nullThis example shows the response you get when trying to set a property to null

Example request

bull POST httplocalhost7474dbdatanodebull Accept applicationjsonbull Content-Type applicationjson

foonull

Example response

bull 400 Bad Requestbull Content-Type applicationjson

message Could not set property foo unsupported type null

exception orgneo4jserverrestwebPropertyValueException Could not set property foo unsupported type null

stacktrace [ orgneo4jserverrestwebDatabaseActionsset(DatabaseActionsjava127) orgneo4jserverrestwebDatabaseActionscreateNode(DatabaseActionsjava182) orgneo4jserverrestwebRestfulGraphDatabasecreateNode(RestfulGraphDatabasejava159) sunreflectNativeMethodAccessorImplinvoke0(Native Method) sunreflectNativeMethodAccessorImplinvoke(NativeMethodAccessorImpljava39) sunreflectDelegatingMethodAccessorImplinvoke(DelegatingMethodAccessorImpljava25) javalangreflectMethodinvoke(Methodjava597) comsunjerseyserverimplmodelmethoddispatchAbstractResourceMethodDispatchProvider$ResponseOutInvoker_dispatch(AbstractResourceMethodDispatchProviderjava184) comsunjerseyserverimplmodelmethoddispatchResourceJavaMethodDispatcherdispatch(ResourceJavaMethodDispatcherjava67) comsunjerseyserverimplurirulesHttpMethodRuleaccept(HttpMethodRulejava276) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesResourceClassRuleaccept(ResourceClassRulejava83) comsunjerseyserverimplurirulesRightHandPathRuleaccept(RightHandPathRulejava133) comsunjerseyserverimplurirulesRootResourceClassesRuleaccept(RootResourceClassesRulejava71) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1171) comsunjerseyserverimplapplicationWebApplicationImpl_handleRequest(WebApplicationImpljava1103) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1053) comsunjerseyserverimplapplicationWebApplicationImplhandleRequest(WebApplicationImpljava1043) comsunjerseyspicontainerservletWebComponentservice(WebComponentjava406) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava477) comsunjerseyspicontainerservletServletContainerservice(ServletContainerjava662) javaxservlethttpHttpServletservice(HttpServletjava820) orgmortbayjettyservletServletHolderhandle(ServletHolderjava511) orgmortbayjettyservletServletHandlerhandle(ServletHandlerjava390) orgmortbayjettyservletSessionHandlerhandle(SessionHandlerjava182) orgmortbayjettyhandlerContextHandlerhandle(ContextHandlerjava765) orgmortbayjettyhandlerHandlerCollectionhandle(HandlerCollectionjava114) orgmortbayjettyhandlerHandlerWrapperhandle(HandlerWrapperjava152) orgmortbayjettyServerhandle(Serverjava326) orgmortbayjettyHttpConnectionhandleRequest(HttpConnectionjava542) orgmortbayjettyHttpConnection$RequestHandlercontent(HttpConnectionjava943) orgmortbayjettyHttpParserparseNext(HttpParserjava756) orgmortbayjettyHttpParserparseAvailable(HttpParserjava212) orgmortbayjettyHttpConnectionhandle(HttpConnectionjava404) orgmortbayjettybioSocketConnector$Connectionrun(SocketConnectorjava228) orgmortbaythreadQueuedThreadPool$PoolThreadrun(QueuedThreadPooljava582) ]

656 Property values can not be nestedNesting properties is not supported You could for example store the nested json as a string instead

Example request

foo bar baz

Example response

message Could not set property foo unsupported type bar=baz

exception orgneo4jserverrestwebPropertyValueException Could not set property foo unsupported type bar=baz

657 Delete all properties from nodeExample request

bull DELETE httplocalhost7474dbdatanode2propertiesbull Accept applicationjson

Example response

REST API

bull 204 No Content

REST API

66 Relationship properties

661 Update relationship propertiesExample request

bull PUT httplocalhost7474dbdatarelationship0properties

jim tobias

Example response

bull 204 No Content

REST API

67 IndexesAn index can contain either nodes or relationships

NoteTo create an index with default configuration simply start using it by adding nodesrelationships to it It will then be automatically created for you

What default configuration means depends on how you have configured your database If you havenrsquotchanged any indexing configuration it means the indexes will be using a Lucene-based backend

If you want to customize the index settings see Section 672 ldquoCreate node index with configurationrdquo

671 Create node index

NoteInstead of creating the index this way you can simply start to use it and it will be createdautomatically

Example request

bull POST httplocalhost7474dbdataindexnode

name favorites

Example response

bull 201 Created

bull Location httplocalhost7474dbdataindexnodefavorites

template httplocalhost7474dbdataindexnodefavoriteskeyvalue

672 Create node index with configurationThis request is only necessary if you want to customize the index settings If you are happy with thedefaults you can just start indexing nodesrelationships as non-existent indexes will automaticallybe created as you do See Section 710 ldquoConfiguration and fulltext indexesrdquo for more information onindex configuration

Example request

namefulltext configtypefulltextproviderlucene

Example response

REST API

bull 201 Created

bull Location httplocalhost7474dbdataindexnodefulltext

template httplocalhost7474dbdataindexnodefulltextkeyvalue

provider lucene

type fulltext

673 Delete node indexExample request

bull DELETE httplocalhost7474dbdataindexnodekvnode

Example response

bull 204 No Content

674 List node indexeshellip

GET $orgneo4jserverrestwebindexnode

throws PropertyValueException

Example request

bull GET httplocalhost7474dbdataindexnode

Example response

bull 200 OK

favorites

provider lucene

type exact

675 List node indexes (empty result)This is an example covering the case where no node index exists

Example request

Example response

REST API

bull 204 No Content

676 Add node to indexAssociates a node with the given keyvalue pair in the given index

NoteSpaces in the URI have to be escaped

CautionThis does not overwrite previous entries If you index the same keyvalueitemcombination twice two index entries are created To do update-type operations you needto delete the old entry before adding a new one

Example request

bull POST httplocalhost7474dbdataindexnodefavoriteskeythe20value

httplocalhost7474dbdatanode0

Example response

bull 201 Created

bull Location httplocalhost7474dbdataindexnodefavoriteskeythe20value0

indexed httplocalhost7474dbdataindexnodefavoriteskeythe20value0

extensions

GraphCloner

REST API

677 Find node by exact match

Example request

bull GET httplocalhost7474dbdataindexnodefavoriteskeythe20value

Example response

bull 200 OK

extensions

GraphCloner

REST API

68 TraversalsTraversals are performed from a start node The traversal is controlled by the URI and the body sentwith the request

responseTypeThe kind of objects in the response is determined by traversereturnType in the URLreturnType can have one of these valuesbull node

bull relationship

bull path

bull fullpath

To decide how the graph should be traversed you can use these parameters in the request body

orderDecides in which order to visit nodes Possible valuesbull breadth_first

bull depth_first

relationshipsDecides which relationship types and directions should be followed The direction can be one ofbull all

bull in

bull out

uniquenessDecides how uniqueness should be calculated Possible valuesbull node_global

bull none

bull relationship_global

bull node_path

bull relationship_path

prune_evaluatorDecides whether the traverser should continue down that path or if it should be pruned so that thetraverser wonrsquot continue down that path You can write your own prune evaluator or use the built-in none prune evaluator

return filterDecides whether the current position should be included in the result You can provide your owncode for this or use one of the built-in filtersbull all

bull all_but_start_node

max_depthIs a short-hand way of specifying a prune evaluator which prunes after a certain depth If notspecified a max depth of 1 is used and if a prune evaluator is specified instead of a max depthno max depth limit is set

The position object in the body of the return filter and prune evaluator is a Path lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbPathhtmlgt objectrepresenting the path from the start node to the current traversal position

REST API

Out of the box the REST API supports JavaScript code in filtersevaluators See the examples for theexact syntax of the request

681 Traversal using a return filterIn this example the none prune evaluator is used and a return filter is supplied The result is to bereturned as nodes and the max depth is set to 3

Example request

bull POST httplocalhost7474dbdatanode20traversenodebull Accept applicationjsonbull Content-Type applicationjson

order breadth_first

return_filter

body positionendNode()getProperty(name)toLowerCase()contains(t)

language javascript

prune_evaluator

name none

language builtin

uniqueness node_global

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

bull 200 OKbull Content-Type applicationjson

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

682 Creating a paged traverserPaged traversers are created by POST-ing a traversal description to the link identified by thepaged_traverser key in a node representation When creating a paged traverser the same optionsapply as for a regular traverser meaning that node path or fullpath can be targeted

Example request

bull POST httplocalhost7474dbdatanode34pagedtraversenodebull Accept applicationjsonbull Content-Type applicationjson

prune_evaluatorlanguagebuiltinnamenonereturn_filterlanguagejavascriptbodypositionendNode()getProperty(name)contains(1)orderdepth_firstrelationshipstypeNEXTdirectionout

Example response

bull 201 Createdbull Content-Type applicationjsonbull Location httplocalhost7474dbdatanode34pagedtraversenode2ee0eb9931bd40758c5254c6057ac119

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

683 Paging through the results of a paged traverserPaged traversers hold state on the server and allow clients to page through the results of a traversalTo progress to the next page of traversal results the client issues a HTTP GET request on the pagedtraversal URI which causes the traversal to fill the next page (or partially fill it if insufficient resultsare available)

Note that if a traverser expires through inactivity it will cause a 404 response on the next GET requestTraversers leases are renewed on every successful access for the same amount of time as originallyspecified

When the paged traverser reaches the end of its results the client can expect a 404 response as thetraverser is disposed by the server

Example request

bull GET httplocalhost7474dbdatanode67pagedtraversenodec61e65ec38764dfbb0117c1f6f894abf

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

684 Paged traverser page sizeThe default page size is 50 items but depending on the application larger or smaller pages sizes mightbe appropriate This can be set by adding a pageSize query parameter

Example request

REST API

bull POST httplocalhost7474dbdatanode544pagedtraversenodepageSize=1bull Accept applicationjsonbull Content-Type applicationjson

Example response

bull 201 Createdbull Content-Type applicationjsonbull Location httplocalhost7474dbdatanode544pagedtraversenode723906ad46b74865b71cba847e423a76

name 1

extensions

GraphCloner

685 Paged traverser timeoutThe default timeout for a paged traverser is 60 seconds but depending on the application larger orsmaller timeouts might be appropriate This can be set by adding a leaseTime query parameter withthe number of seconds the paged traverser should last

Example request

bull POST httplocalhost7474dbdatanode577pagedtraversenodeleaseTime=10bull Accept applicationjsonbull Content-Type applicationjson

Example response

bull 201 Created

REST API

bull Content-Type applicationjsonbull Location httplocalhost7474dbdatanode577pagedtraversenode6de04c6f439d403a8c7e10d8c738ab57

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

69 Built-in Graph AlgorithmsNeo4j comes with a number of built-in graph algorithms They are performed from a start node Thetraversal is controlled by the URI and the body sent with the request

algorithmThe algorithm to choose If not set default is shortestPath algorithm can have one of thesevalues

bull shortestPath

bull allSimplePaths

bull allPaths

bull dijkstra (optional with cost_property and default_cost parameters)

max_depthThe maximum depth as an integer for the algorithms like ShortestPath where applicable Defaultis 1

691 Find all shortest pathsThe shortestPath algorithm can find multiple paths between the same nodes like in this example

Example request

bull POST httplocalhost7474dbdatanode7paths

tohttplocalhost7474dbdatanode2 max_depth3 relationshipstypeto directionout algorithmshortestPath

Example response

bull 200 OK

nodes [ httplocalhost7474dbdatanode7 httplocalhost7474dbdatanode3 httplocalhost7474dbdatanode2 ]

length 2

relationships [ httplocalhost7474dbdatarelationship1 httplocalhost7474dbdatarelationship7 ]

length 2

692 Find one of the shortest paths between nodesIf no path algorithm is specified a ShortestPath algorithm with a max depth of 1 will be chosen Inthis example the max_depth is set to 3 in order to find the shortest path between 3 linked nodes

Example request

bull POST httplocalhost7474dbdatanode14path

REST API

Example response

bull 200 OK

length 2

693 Execute a Dijkstra algorithm with similar weights on relationshipsExample request

tohttplocalhost7474dbdatanode32 cost_propertycost relationshipstypeto directionout algorithmdijkstra

Example response

bull 200 OK

weight 20

length 2

694 Execute a Dijkstra algorithm with weights on relationshipsExample request

Example response

bull 200 OK

weight 60

REST API

nodes [ httplocalhost7474dbdatanode20 httplocalhost7474dbdatanode21 httplocalhost7474dbdatanode18 httplocalhost7474dbdatanode19 httplocalhost7474dbdatanode16 httplocalhost7474dbdatanode17 httplocalhost7474dbdatanode23 ]

length 6

relationships [ httplocalhost7474dbdatarelationship20 httplocalhost7474dbdatarelationship22 httplocalhost7474dbdatarelationship24 httplocalhost7474dbdatarelationship27 httplocalhost7474dbdatarelationship29 httplocalhost7474dbdatarelationship30 ]

REST API

610 Batch operations

CautionBatch support is currently experimental Expect this part of the API to change

6101 Execute multiple operations in batchThis lets you execute multiple API calls through a single HTTP call significantly improvingperformance for large insert and update operations

The batch service expects an array of job descriptions as input each job description describing anaction to be performed via the normal server API

This service is transactional If any of the operations performed fails (returns a non-2xx HTTP statuscode) the transaction will be rolled back and all changes will be undone

Each job description should contain a path attribute with a value relative to the data API root (sohttplocalhostdbdatanode becomes just node) and a method attribute containing HTTP verb touse

Optionally you may provide a body attribute and an id attribute to help you keep track of responsesalthough responses are guaranteed to be returned in the same order the job descriptions are received

The following figure outlines the different parts of the job descriptions

Example request

bull POST httplocalhost7474dbdatabatch

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

[id0fromnode0propertiesid1body

extensions

GraphCloner

fromnode0id2locationhttplocalhost7474dbdatanode3body

extensions

REST API

GraphCloner

fromnodeid3locationhttplocalhost7474dbdatanode4body

extensions

GraphCloner

fromnode]

6102 Refer to items created earlier in the same batch jobThe batch operation API allows you to refer to the URI returned from a created resource in subsequentjob descriptions within the same batch call

Use the [JOB ID] special syntax to inject URIs from created resources into JSON strings insubsequent job descriptions

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

toindexrelationshipmy_relsnamebob

Example response

bull 200 OK

[id0locationhttplocalhost7474dbdatanode7body

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

fromnodeid3locationhttplocalhost7474dbdatarelationship1body

name bob

type KNOWS

extensions

fromhttplocalhost7474dbdatanode7relationshipsid4locationhttplocalhost7474dbdataindexrelationshipmy_relsnamebob1body

indexed httplocalhost7474dbdataindexrelationshipmy_relsnamebob1

name bob

type KNOWS

extensions

fromindexrelationshipmy_relsnamebob]

REST API

611 Gremlin PluginGremlin lthttpgremlintinkerpopcomgt is a Groovy based Graph Traversal Language and provides avery expressive way of explicitly scripting traversals through a Neo4j graph

The Neo4j Gremlin Plugin provides an endpoint to send Gremlin scripts to the Neo4j Serverhave them executed on the server database and return the results as Neo4j Node and Relationshiprepresentations thus keeping the types throughout the REST API consistent This results is quiteverbose listings when returning Neo4j Node Relationship or Graph representations On the otherhand just return properties like in the Section 6114 ldquoSend a Gremlin Script - JSON encoded withtable resultrdquo example for returns tailored to specific needs

6111 Send a Gremlin Script - URL encodedSend a Gremlin Script URL-encoded with UTF-8 encoding eg the equivalent of the Gremlin Scripti = gv(1)ioutEinV

Example request

bull POST httplocalhost7474dbdataextGremlinPlugingraphdbexecute_script

bull Content-Type applicationx-www-form-urlencoded

script=i+3D+gv282293BioutEinV

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

6112 Load a sample graph graphImport a graph form a GraphML lthttpgraphmlgraphdrawingorggt file can be achieved through theGremlin GraphMLReader The following script imports 3 nodes into Neo4j and then returns a list ofall nodes in the graph

Example request

bull POST httplocalhost7474dbdataextGremlinPlugingraphdbexecute_scriptbull Accept applicationjsonbull Content-Type applicationjson

scriptGraphMLReaderinputGraph(g new URL(httpsrawgithubcomneo4jgremlin-pluginmastersrcdatagraphml1xml)openStream())gV

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

6113 Sort a result using raw Groovy operationsThe following script returns a sorted list of all nodes connected via outgoing relationships to node 1sorted by their name-property

Example request

scriptgv(8)outEinVsortitnametoList()

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

6114 Send a Gremlin Script - JSON encoded with table resultTo send a Script JSON encoded set the payload Content-Type Header In this example find all thethings that my friends like and return a table listing my friends by their name and the names of thethings they like in a table with two columns ignoring the third named step variable I Remember thateverything in Gremlin is an iterator - in order to populate the result table t iterate through the pipeswith gtgt -1

Example request

scripti = gv(11)t= new Table()ias(I)out(know)as(friend)out(like)as(likes)table(t[friendlikes])itnameitname gtgt -1t

Example response

bull 200 OK

data [ [ Joe cats ] [ Joe dogs ] ]

columns [ friend likes ]

REST API

612 Cypher PluginThe Neo4j Cypher Plugin enables querying with the Chapter 4 Cypher Query Language possibleThe results are returned as a list of string headers (columns) and a data part consisting of a list of allrows every row consisting of a list of REST representations of the field value - Node Relationshipor any simple value like String

6121 Send a QueryA simple query returning all nodes connected to node 1 returning the node and the name property ifit exists otherwise null

Example request

bull POST httplocalhost7474dbdataextCypherPlugingraphdbexecute_query

query start x = (3) match (x) --gt (n) return nname nage

Example response

bull 200 OK

data [ [ you null ] [ him null ] ]

columns [ nname nage ]

Chapter 7 Indexing

Indexing in Neo4j can be done in two different ways

1 The database itself is a natural index consisting of its relationships of different types betweennodes For example a tree structure can be layered on top of the data and used for index lookupsperformed by a traverser

2 Separate index engines can be used with Apache Lucene lthttpluceneapacheorgjava3_1_0indexhtmlgt being the default backend included with Neo4j

This chapter demonstrate how to use the second type of indexing focusing on Lucene

Indexing

71 IntroductionIndexing operations are part of the Neo4j index API lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexpackage-summaryhtmlgt

Each index is tied to a unique user-specified name (for example first_name or books) andcan index either nodes lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbNodehtmlgt or relationships lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbRelationshiphtmlgt

The default index implementation is provided by the neo4j-lucene-index component whichis included in the standard Neo4j download It can also be downloaded separately from httprepo1mavenorgmaven2orgneo4jneo4j-lucene-index For Maven users the neo4j-lucene-index component has the coordinates orgneo4jneo4j-lucene-index and should be usedwith the same version of orgneo4jneo4j-kernel Different versions of the index and kernelcomponents are not compatible in the general case Both components are included transitively by theorgneo4jneo4jpom artifact which makes it simple to keep the versions in sync

NoteAll modifying index operations must be performed inside a transaction as with anymutating operation in Neo4j

Indexing

72 CreateAn index is created if it doesnrsquot exist when you ask for it Unless you give it a custom configuration itwill be created with default configuration and backend

To set the stage for our examples letrsquos create some indexes to begin with

IndexManager index = graphDbindex()

IndexltNodegt actors = indexforNodes( actors )

IndexltNodegt movies = indexforNodes( movies )

RelationshipIndex roles = indexforRelationships( roles )

This will create two node indexes and one relationship index with default configuration SeeSection 78 ldquoRelationship indexesrdquo for more information specific to relationship indexes

See Section 710 ldquoConfiguration and fulltext indexesrdquo for how to create fulltext indexes

You can also check if an index exists like this

boolean indexExists = indexexistsForNodes( actors )

Indexing

73 DeleteIndexes can be deleted When deleting the entire contents of the index will be removed as well as itsassociated configuration A new index can be created with the same name at a later point in time

actorsdelete()

Note that the actual deletion of the index is made during the commit of the surrounding transactionCalls made to such an index instance after delete() lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmldelete2829gt has been called are invalid inside thattransaction as well as outside (if the transaction is successful) but will become valid again if thetransaction is rolled back

Indexing

74 AddEach index supports associating any number of key-value pairs with any number of entities (nodes orrelationships) where each association between entity and key-value pair is performed individually Tobegin with letrsquos add a few nodes to the indexes

Actors

Node reeves = graphDbcreateNode()

actorsadd( reeves name Keanu Reeves )

Node bellucci = graphDbcreateNode()

actorsadd( bellucci name Monica Bellucci )

multiple values for a field

actorsadd( bellucci name La Bellucci )

Movies

Node theMatrix = graphDbcreateNode()

moviesadd( theMatrix title The Matrix )

moviesadd( theMatrix year 1999 )

Node theMatrixReloaded = graphDbcreateNode()

moviesadd( theMatrixReloaded title The Matrix Reloaded )

moviesadd( theMatrixReloaded year 2003 )

Node malena = graphDbcreateNode()

moviesadd( malena title Malegravena )

moviesadd( malena year 2000 )

Note that there can be multiple values associated with the same entity and key

Next up wersquoll create relationships and index them as well

we need a relationship type

DynamicRelationshipType ACTS_IN = DynamicRelationshipTypewithName( ACTS_IN )

create relationships

Relationship role1 = reevescreateRelationshipTo( theMatrix ACTS_IN )

rolesadd( role1 name Neo )

Relationship role2 = reevescreateRelationshipTo( theMatrixReloaded ACTS_IN )

Relationship role3 = belluccicreateRelationshipTo( theMatrixReloaded ACTS_IN )

rolesadd( role3 name Persephone )

Relationship role4 = belluccicreateRelationshipTo( malena ACTS_IN )

rolesadd( role4 name Malegravena Scordia )

Assuming we set the same key-value pairs as properties as well our example graph looks like this

Indexing

75 RemoveRemoving lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmlremove28T20javalangString20javalangObject29gt from an index is similar toadding but can be done by supplying one of the following combinations of arguments

bull entity

bull entity key

bull entity key value

completely remove bellucci from the actors index

actorsremove( bellucci )

remove any name entry of bellucci from the actors index

actorsremove( bellucci name )

remove the name -gt La Bellucci entry of bellucci

actorsremove( bellucci name La Bellucci )

Indexing

76 Update

ImportantTo update an index entry old one must be removed and a new one added

Remember that a node or relationship can be associated with any number of key-value pairs in anindex which means that you can index a node or relationship with many key-value pairs that havethe same key In the case where a property value changes and yoursquod like to update the index itrsquos notenough to just index the new value - yoursquoll have to remove the old value as well

Herersquos a code example for that demonstrates how itrsquos done

create a node with a property

Node fishburn = graphDbcreateNode()

fishburnsetProperty( name Fishburn )

index it

actorsadd( fishburn name fishburngetProperty( name ) )

update the index entry

actorsremove( fishburn name fishburngetProperty( name ) )

fishburnsetProperty( name Laurence Fishburn )

Indexing

77 SearchAn index can be searched in two ways get lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmlget28javalangString20javalangObject29gt and querylthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmlquery28javalangString20javalangObject29gt The get method will return exact matches tothe given key-value pair whereas query exposes querying capabilities directly from the backendused by the index For example the Lucene query syntax lthttpluceneapacheorgjava3_1_0queryparsersyntaxhtmlgt can be used directly with the default indexing backend

771 GetThis is how to search for a single exact match

IndexHitsltNodegt hits = actorsget( name Keanu Reeves )

Node reeves = hitsgetSingle()

IndexHits lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexHitshtmlgt is an Iterable with some additional useful methods For examplegetSingle() lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexHitshtmlgetSingle2829gt returns the first and only item from the result iterator or null ifthere isnrsquot any hit

Herersquos how to get a single relationship by exact matching and retrieve its start and end nodes

Relationship persephone = rolesget( name Persephone )getSingle()

Node actor = persephonegetStartNode()

Node movie = persephonegetEndNode()

Finally we can iterate over all exact matches from a relationship index

for ( Relationship role rolesget( name Neo ) )

this will give us Reeves twice

Node reeves = rolegetStartNode()

ImportantIn you donrsquot iterate through all the hits IndexHitsclose() lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexHitshtmlclose2829gt must becalled explicitly

772 QueryThere are two query methods one which uses a key-value signature where the value represents aquery for values with the given key only The other method is more generic and supports querying formore than one key-value pair in the same query

Herersquos an example using the key-query option

for ( Node actor actorsquery( name e ) )

This will return Reeves and Bellucci

In the following example the query uses multiple keys

for ( Node movie moviesquery( titleMatrix AND year1999 ) )

This will return The Matrix from 1999 only

Indexing

NoteBeginning a wildcard search with or is discouraged by Lucene but willnevertheless work

CautionYou canrsquot have any whitespace in the search term with this syntax See Section 7113ldquoQuerying with Lucene Query objectsrdquo for how to do that

Indexing

78 Relationship indexesAn index for relationships is just like an index for nodes extended by providing support to constraina search to relationships with a specific start andor end nodes These extra methods reside in theRelationshipIndex lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexRelationshipIndexhtmlgt interface which extends IndexltRelationshipgt lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmlgt

Example of querying a relationship index

find relationships filtering on start node

using exact matches

IndexHitsltRelationshipgt reevesAsNeoHits

reevesAsNeoHits = rolesget( name Neo reeves null )

Relationship reevesAsNeo = reevesAsNeoHitsiterator()next()

reevesAsNeoHitsclose()

find relationships filtering on end node

using a query

IndexHitsltRelationshipgt matrixNeoHits

matrixNeoHits = rolesquery( name eo null theMatrix )

Relationship matrixNeo = matrixNeoHitsiterator()next()

matrixNeoHitsclose()

And herersquos an example for the special case of searching for a specific relationship type

using a relationship type

this is how to add it to the index

rolesadd( reevesAsNeo type reevesAsNeogetType()name() )

Note that to use a compound query we cant combine committed

and uncommitted index entries so well commit before querying

txsuccess()

txfinish()

and now we can search for it

IndexHitsltRelationshipgt typeHits

typeHits = rolesquery( typeACTS_IN AND nameNeo null theMatrix )

Relationship typeNeo = typeHitsiterator()next()

typeHitsclose()

Such an index can be useful if your domain has nodes with a very large number of relationshipsbetween them since it reduces the search time for a relationship between two nodes A good examplewhere this approach pays dividends is in time series data where we have readings represented as arelationship per occurrence

Indexing

79 ScoresThe IndexHits interface exposes scoring lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexHitshtmlcurrentScore2829gt so that the index can communicatescores for the hits Note that the result is not sorted by the score unless you explicitly specify that SeeSection 7112 ldquoSortingrdquo for how to sort by score

IndexHitsltNodegt hits = moviesquery( title The )

for ( Node movie hits )

Systemoutprintln( moviegetProperty( title ) + + hitscurrentScore() )

Indexing

710 Configuration and fulltext indexesAt the time of creation extra configuration can be specified to control the behavior of the index andwhich backend to use For example to create a Lucene fulltext index

IndexltNodegt fulltextMovies = indexforNodes( movies-fulltext

MapUtilstringMap( IndexManagerPROVIDER lucene type fulltext ) )

fulltextMoviesadd( theMatrix title The Matrix )

fulltextMoviesadd( theMatrixReloaded title The Matrix Reloaded )

search in the fulltext index

Node found = fulltextMoviesquery( title reloAdEd )getSingle()

TipIn order to search for tokenized words the query method has to be used The get methodwill only match the full string value not the tokens

The configuration of the index is persisted once the index has been created The providerconfiguration key is interpreted by Neo4j but any other configuration is passed onto the backendindex (eg Lucene) to interpret

Table 71 Lucene indexing configuration parameters

type exact fulltext exact is the default and uses a Lucenekeyword analyzer lthttpluceneapacheorgjava3_1_0apicoreorgapacheluceneanalysisKeywordAnalyzerhtmlgt fulltext uses a white-space tokenizer in its analyzer

to_lower_case true false This parameter goes together with typefulltext and converts values to lower caseduring both additions and querying making theindex case insensitive Defaults to true

analyzer the full class name ofan Analyzer lthttpluceneapacheorgjava3_1_0apicoreorgapacheluceneanalysisAnalyzerhtmlgt

Overrides the type so that a custom analyzercan be used Note to_lower_case still affectslowercasing of string queries If the customanalyzer uppercases the indexed tokens stringqueries will not match as expected

Indexing

711 Extra features for Lucene indexes

7111 Numeric rangesLucene supports smart indexing of numbers querying for ranges and sorting such results and so doesits backend for Neo4j To mark a value so that it is indexed as a numeric value we can make use ofthe ValueContext lthttpcomponentsneo4jorgneo4j-lucene-index14M06apidocsorgneo4jindexluceneValueContexthtmlgt class like this

moviesadd( theMatrix year-numeric new ValueContext( 1999 )indexNumeric() )

moviesadd( theMatrixReloaded year-numeric new ValueContext( 2003 )indexNumeric() )

moviesadd( malena year-numeric new ValueContext( 2000 )indexNumeric() )

int from = 1997

int to = 1999

hits = moviesquery( QueryContextnumericRange( year-numeric from to ) )

NoteThe same type must be used for indexing and querying That is you canrsquot index a value asa Long and then query the index using an Integer

By giving null as fromto argument an open ended query is created In the following example we aredoing that and have added sorting to the query as well

hits = moviesquery(

QueryContextnumericRange( year-numeric from null )

sortNumeric( year-numeric false ) )

Fromto in the ranges defaults to be inclusive but you can change this behavior by using two extraparameters

moviesadd( theMatrix score new ValueContext( 87 )indexNumeric() )

moviesadd( theMatrixReloaded score new ValueContext( 71 )indexNumeric() )

moviesadd( malena score new ValueContext( 74 )indexNumeric() )

include 80 exclude 90

hits = moviesquery( QueryContextnumericRange( score 80 90 true false ) )

7112 SortingLucene performs sorting very well and that is also exposed in the index backend through theQueryContext lthttpcomponentsneo4jorgneo4j-lucene-index14M06apidocsorgneo4jindexluceneQueryContexthtmlgt class

hits = moviesquery( title new QueryContext( )sort( title ) )

for ( Node hit hits )

all movies with a title in the index ordered by title

hits = moviesquery( new QueryContext( title )sort( year title ) )

all movies with a title in the index ordered by year then title

We sort the results by relevance (score) like this

hits = moviesquery( title new QueryContext( The )sortByScore() )

Indexing

hits sorted by relevance (score)

7113 Querying with Lucene Query objectsInstead of passing in Lucene query syntax queries you can instantiate such queries programmaticallyand pass in as argument for example

a TermQuery will give exact matches

Node actor = actorsquery( new TermQuery( new Term( name Keanu Reeves ) ) )getSingle()

Note that the TermQuery lthttpluceneapacheorgjava3_1_0apicoreorgapachelucenesearchTermQueryhtmlgt is basically the same thing as using the get method on the index

This is how to perform wildcard searches using Lucene Query Objects

hits = moviesquery( new WildcardQuery( new Term( title The Matrix ) ) )

Systemoutprintln( moviegetProperty( title ) )

Note that this allows for whitespace in the search string

7114 Compound queriesLucene supports querying for multiple terms in the same query like so

hits = moviesquery( titleMatrix AND year1999 )

CautionCompound queries canrsquot search across committed index entries and those who havenrsquot gotcommitted yet at the same time

7115 Default operatorThe default operator (that is whether AND or OR is used in between different terms) in a query is ORChanging that behavior is also done via the QueryContext lthttpcomponentsneo4jorgneo4j-lucene-index14M06apidocsorgneo4jindexluceneQueryContexthtmlgt class

QueryContext query = new QueryContext( titleMatrix year1999 )defaultOperator( OperatorAND )

hits = moviesquery( query )

7116 CachingIf your index lookups becomes a performance bottle neck caching can be enabled for certain keys incertain indexes (key locations) to speed up get requests The caching is implemented with an LRUlthttpenwikipediaorgwikiCache_algorithmsLeast_Recently_Usedgt cache so that only the mostrecently accessed results are cached (with results meaning a query result of a get request not asingle entity) You can control the size of the cache (the maximum number of results) per index key

IndexltNodegt index = graphDbindex()forNodes( actors )

( (LuceneIndexltNodegt) index )setCacheCapacity( name 300000 )

CautionThis setting is not persisted after shutting down the database This means set this valueafter each startup of the database if you want to keep it

Indexing

712 Batch insertionNeo4j has a batch insertion mode intended for initial imports which must run in a singlethread and bypasses transactions and other checks in favor of performance Indexingduring batch insertion is done using BatchInserterIndex lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexBatchInserterIndexhtmlgt which are provided viaBatchInserterIndexProvider lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexBatchInserterIndexProviderhtmlgt An example

BatchInserter inserter = new BatchInserterImpl( targetneo4jdb-batchinsert )

BatchInserterIndexProvider indexProvider = new LuceneBatchInserterIndexProvider( inserter )

BatchInserterIndex actors = indexProvidernodeIndex( actors MapUtilstringMap( type exact ) )

actorssetCacheCapacity( name 100000 )

MapltString Objectgt properties = MapUtilmap( name Keanu Reeves )

long node = insertercreateNode( properties )

actorsadd( node properties )

Make sure to shut down the index provider

indexProvidershutdown()

insertershutdown()

The configuration parameters are the same as mentioned in Section 710 ldquoConfiguration and fulltextindexesrdquo

7121 Best practicesHere are some pointers to get the most performance out of BatchInserterIndex

bull Try to avoid flushing lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexBatchInserterIndexhtmlflush2829gt too often because each flush will result in alladditions (since last flush) to be visible to the querying methods and publishing those changes canbe a performance penalty

bull Have (as big as possible) phases where one phase is either only writes or only reads and donrsquotforget to flush after a write phase so that those changes becomes visible to the querying methods

bull Enable caching lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexBatchInserterIndexhtmlsetCacheCapacity28javalangString20int29gt for keys you knowyoursquore going to do lookups for later on to increase performance significantly (though insertionperformance may degrade slightly)

Indexing

713 Auto IndexingNeo4j provides the ability to have an index that automatically follows property values as they areadded deleted and changed on database primitives This functionality is called auto indexing and iscontrolled both from the database configuration Map and through its own API

CautionThis is an experimental feature Expect changes in the API and do not rely on it forproduction data handling

7131 ConfigurationBy default Auto Indexing is off for both Nodes and Relationships To enable it ondatabase startup set the configuration options ConfigNODE_AUTO_INDEXING andConfigRELATIONSHIP_AUTO_INDEXING to the string true

If you just enable auto indexing as above then still no property will be auto indexed To define whichproperty names you want the auto indexer to monitor as a configuration parameter set the ConfigNODERELATIONSHIP_KEYS_INDEXABLE option to a String that is a comma separated concatenationof the property names you want auto indexed

Creating the configuration adding nodeProp1 and nodeProp2 as

auto indexed properties for Nodes and relProp1 and relProp2 as

auto indexed properties for Relationships Only those will be

indexed We also have to enable auto indexing for both these

primitives explicitly

MapltString Stringgt config = new HashMapltString Stringgt()

configput( ConfigNODE_KEYS_INDEXABLE nodeProp1 nodeProp2 )

configput( ConfigRELATIONSHIP_KEYS_INDEXABLE relProp1 relProp2 )

configput( ConfigNODE_AUTO_INDEXING true )

configput( ConfigRELATIONSHIP_AUTO_INDEXING true )

EmbeddedGraphDatabase graphDb = new EmbeddedGraphDatabase(

getStoreDir( testConfig ) config )

Transaction tx = graphDbbeginTx()

Node node1 = null node2 = null

Relationship rel = null

Create the primitives

node1 = graphDbcreateNode()

rel = node1createRelationshipTo( node2

DynamicRelationshipTypewithName( DYNAMIC ) )

Add indexable and non-indexable properties

node1setProperty( nodeProp1 nodeProp1Value )

node1setProperty( nonIndexed nodeProp2NonIndexedValue )

relsetProperty( relProp1 relProp1Value )

relsetProperty( relPropNonIndexed relPropValueNonIndexed )

Make things persistent

txsuccess()

catch ( Exception e )

txfailure()

Indexing

finally

txfinish()

7132 SearchThe usefulness of the auto indexing functionality comes of course from the ability to actuallyquery the index and retrieve results To that end you can acquire a ReadableIndex objectfrom the AutoIndexer that exposes all the query and get methods of a full Index lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbindexIndexhtmlgt with exactly thesame functionality Continuing from the previous example accessing the index is done like this

Get the Node auto index

ReadableIndexltNodegt autoNodeIndex = graphDbindex()getNodeAutoIndexer()getAutoIndex()

node1 and node2 both had auto indexed properties get them

assertEquals( node1

autoNodeIndexget( nodeProp1 nodeProp1Value )getSingle() )

assertEquals( node2

node2 also had a property that should be ignored

assertFalse( autoNodeIndexget( nonIndexed

nodeProp2NonIndexedValue )hasNext() )

Get the relationship auto index

ReadableIndexltRelationshipgt autoRelIndex = graphDbindex()getRelationshipAutoIndexer()getAutoIndex()

One property was set for auto indexing

assertEquals( rel

autoRelIndexget( relProp1 relProp1Value )getSingle() )

The rest should be ignored

assertFalse( autoRelIndexget( relPropNonIndexed

relPropValueNonIndexed )hasNext() )

7133 Runtime ConfigurationThe same options that are available during database creation via the configuration can also be setduring runtime via the AutoIndexer API

Gaining access to the AutoIndexer API and adding two Node and one +Relationship properties toauto index is done like so

Start without any configuration

getStoreDir( testAPI ) )

Get the Node AutoIndexer set nodeProp1 and nodeProp2 as auto

indexed

AutoIndexerltNodegt nodeAutoIndexer = graphDbindex()getNodeAutoIndexer()

nodeAutoIndexerstartAutoIndexingProperty( nodeProp1 )

Get the Relationship AutoIndexer

AutoIndexerltRelationshipgt relAutoIndexer = graphDbindex()getRelationshipAutoIndexer()

relAutoIndexerstartAutoIndexingProperty( relProp1 )

None of the AutoIndexers are enabled so far Do that now

nodeAutoIndexersetEnabled( true )

relAutoIndexersetEnabled( true )

Parameters to the AutoIndexers passed through the Configuration and settings made through the APIare cumulative So you can set some beforehand known settings do runtime checks to augment the

Indexing

initial configuration and then enable the desired auto indexers - the final configuration is the sameregardless of the method used to reach it

7134 Updating the Auto IndexUpdates to the auto indexed properties happen of course automatically as you update them Removalof properties from the auto index happens for two reasons One is that you actually removed theproperty The other is that you stopped autoindexing on a property When the latter happens anyprimitive you touch and it has that property it is removed from the auto index regardless of anyoperations on the property When you start or stop auto indexing on a property no auto updateoperation happens currently If you need to change the set of auto indexed properties and have themre-indexed you currently have to do this by hand An example will illustrate the above better

Creating the configuration

getStoreDir( mutations ) config )

Node node1 = null node2 = null node3 = null node4 = null

txsuccess()

txfailure()

finally

txfinish()

Here both nodes are indexed To demonstrate removal we stop

autoindexing nodeProp1

nodeAutoIndexerstopAutoIndexingProperty( nodeProp1 )

tx = graphDbbeginTx()

Indexing

nodeProp1 is no longer auto indexed It will be

removed regardless Note that node3 will remain

node1setProperty( nodeProp1 nodeProp1Value2 )

node2 will be auto updated

remove node4 property nodeProp2 from index

node4removeProperty( nodeProp2 )

txsuccess()

txfailure()

finally

txfinish()

Verify

ReadableIndexltNodegt nodeAutoIndex = nodeAutoIndexergetAutoIndex()

node1 is completely gone

assertFalse( nodeAutoIndexget( nodeProp1 nodeProp1Value )hasNext() )

assertFalse( nodeAutoIndexget( nodeProp1 nodeProp1Value2 )hasNext() )

node2 is updated

assertEquals( node2

nodeAutoIndexget( nodeProp2 nodeProp2Value2 )getSingle() )

node3 is still there despite its nodeProp1 property not being monitored

any more because it was not touched in contrast with node1

assertEquals( node3

nodeAutoIndexget( nodeProp1 nodeProp3Value )getSingle() )

Finally node4 is removed because the property was removed

CautionIf you start the database with auto indexing enabled but different auto indexed propertiesthan the last run then already auto-indexed entities will be deleted as you work with themMake sure that the monitored set is what you want before enabling the functionality

7135 Low level detailsCurrently the AutoIndexer functionality is implemented as a TransactionEventHandlerlthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbeventTransactionEventHandlerhtmlgt that executes on beforeCommit() of every transaction TheTransactionData lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbeventTransactionDatahtmlgt object is queried for all modified (added deleted and changed)properties of the primitives supported by the AutoIndexer and adds and removes it based on thecurrent configuration This means that the auto indexing happens on successful finish() lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphdbTransactionhtmlfinish2829gtof the transaction and before that the changes are not visible

Chapter 8 Graph Algorithms

Neo4j graph algorithms is a component that contains Neo4j implementations of some commonalgorithms for graphs It includes algorithms like

bull Shortest paths

bull all paths

bull all simple paths

bull Dijkstra and

bull A

Graph Algorithms

81 IntroductionThe graph algorithms are found in the neo4j-graph-algo component which is included in thestandard Neo4j download

bull Javadocs lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphalgopackage-summaryhtmlgt

bull Download lthttpsearchmavenorgsearch7Cgav7C17Cg3A22orgneo4j2220AND20a3A22neo4j-graph-algo22gt

bull Source code lthttpsgithubcomneo4jcommunitytree14M06graph-algogt

For information on how to use neo4j-graph-algo as a dependency with Maven and other dependencymanagement tools see orgneo4jneo4j-graph-algo lthttpsearchmavenorgsearch7Cgav7C17Cg3A22orgneo4j2220AND20a3A22neo4j-graph-algo22gt Note that itshould be used with the same version of orgneo4jneo4j-kernel lthttpsearchmavenorgsearch7Cgav7C17Cg3A22orgneo4j2220AND20a3A22neo4j-kernel22gt Differentversions of the graph-algo and kernel components are not compatible in the general case Bothcomponents are included transitively by the orgneo4jneo4j lthttpsearchmavenorgsearch7Cgav7C17Cg3A22orgneo4j2220AND20a3A22neo4j22gt artifact which makesit simple to keep the versions in sync

The starting point to find and use graph algorithms is GraphAlgoFactory lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jgraphalgo

GraphAlgoFactoryhtmlgt

For examples see Section 126 ldquoGraph Algorithm examplesrdquo

Chapter 9 High Availability

Neo4j High Availability or ldquoNeo4j HArdquo provides the following two main features

1 It enables a fault-tolerant database architecture where several Neo4j slave databases can beconfigured to be exact replicas of a single Neo4j master database This allows the end-user systemto be fully functional and both read and write to the database in the event of hardware failure

2 It enables a horizontally scaling read-mostly architecture that enables the system to handle moreread load than a single Neo4j database instance can handle

High Availability

91 ArchitectureNeo4j HA has been designed to make the transition from single machine to multi machine operationsimple by not having to change the already existing application

Consider an existing application with Neo4j embedded and running on a single machine To deploysuch an application in a multi machine setup the only required change is to switch the creation of theGraphDatabaseService from EmbeddedGraphDatabase to HighlyAvailableGraphDatabase Sinceboth implement the same interface no additional changes are required

Figure 91 Typical setup when running multiple Neo4j instances in HA mode

When running Neo4j in HA mode there is always a single master and zero or more slaves Comparedto other master-slave replication setups Neo4j HA can handle writes on a slave so there is no need toredirect writes to the master

A slave will handle writes by synchronizing with the master to preserve consistency Updates willhowever propagate from the master to other slaves eventually so a write from one slave is notimmediately visible on all other slaves This is the only difference between multiple machines runningin HA mode compared to single machine operation All other ACID characteristics are the same

High Availability

92 Setup and configurationNeo4j HA can be set up to accommodate differing requirements for load fault tolerance and availablehardware

Within a cluster Neo4j HA uses Apache ZooKeeper 1 for master election and propagation ofgeneral cluster and machine status information ZooKeeper can be seen as a distributed coordinationservice Neo4j HA requires a ZooKeeper service for initial master election new master election(current master failing) and to publish general status information about the current Neo4j HAcluster (for example when a machine joined or left the cluster) Read operations through theGraphDatabaseService API will always work and even writes can survive ZooKeeper failures if amaster is present

ZooKeeper requires a majority of the ZooKeeper instances to be available to operate properly Thismeans that the number of ZooKeeper instances should always be an odd number since that will makebest use of available hardware

To further clarify the fault tolerance characteristics of Neo4j HA here are a few example setups

921 Small

bull 3 physical (or virtual) machinesbull 1 ZooKeeper instance running on each machinebull 1 Neo4j HA instance running on each machine

This setup is conservative in the use of hardware while being able to handle moderate read load It canfully operate when at least 2 of the ZooKeeper instances are running Since the ZooKeeper service andNeo4j HA are running together on each machine this will in most scenarios mean that only one serveris allowed to go down

922 Medium

bull 5-7+ machinesbull ZooKeeper running on 3 5 or 7 machinesbull Neo4j HA can run on 5+ machines

This setup may mean that two different machine setups have to be managed (some machines run bothZooKeeper and Neo4j HA) The fault tolerance will depend on how many machines there are that arerunning ZooKeeper With 3 ZooKeeper instances the cluster can survive one ZooKeeper going downwith 5 it can survive 2 and with 7 it can handle 3 ZooKeeper instances failing The number of Neo4jHA instances that can fail for normal operations is theoretically all but 1 (but for each required masterelection the ZooKeeper service must be available)

923 Large

bull 8+ total machinesbull 3+ Neo4j HA machinesbull 5+ Zookeeper on separate dedicated machines

In this setup all ZooKeeper instances are running on separate machines as a dedicated ZooKeeperservice The dedicated ZooKeeper cluster can handle half of the instances minus 1 going down The

1httphadoopapacheorgzookeeper

High Availability

Neo4j HA cluster will be able to operate with at least a single live machine Adding more Neo4j HAinstances is very easy in this setup since Zookeeper is operating as a separate service

924 Installation NotesFor installation instructions of a High Availability cluster please visit the Neo4j Wiki 2

Note that while the HighlyAvailableGraphDatabase supports the same API as theEmbeddedGraphDatabase it does have additional configuration parameters

Table 91 HighlyAvailableGraphDatabase configuration parameters

Parameter Name Value Example value Required

ha machine_id integer gt= 0 1 yes

ha server (auto-discovered) hostamp port to bind whenacting as master

my-domain com6001 no

ha zoo_keeper_servers comma delimitedzookeeper connections

localhost2181

localhost2182

localhost2183

ha pull_interval interval for pollingmaster from a slave inseconds

2httpwikineo4jorgcontentHigh_Availability_Cluster

High Availability

93 How Neo4j HA operatesA Neo4j HA cluster operates cooperatively coordinating activity through Zookeeper

On startup a Neo4j HA instance will connect to the ZooKeeper service to register itself and ask whois master If some other machine is master the new instance will start as slave and connect to thatmaster If the machine starting up was the first to register mdash or should become master according to themaster election algorithm mdash it will start as master

When performing a write transaction on a slave each write operation will be synchronized with themaster (locks will be acquired on both master and slave) When the transaction commits it will firstoccur on the master If the master commit is successful the transaction will be committed on the slaveas well To ensure consistency a slave has to be up to date with the master before performing a writeoperation This is built into the communication protocol between the slave and master so that updateswill happen automatically if needed

When performing a write on the master it will execute in the same way as running in normalembedded mode Currently the master will not push updates to the slave Instead slaves can beconfigured to have a pull interval Without polling updates will only happen on slaves whenever theysynchronize a write with the master

Having all writes go through slaves has the benefit that the data will be replicated on two machinesThis is recommended to avoid rollbacks in case of a master failure that could potentially happen whenthe new master is elected

Whenever a machine becomes unavailable the ZooKeeper service will detect that and remove itfrom the cluster If the master goes down a new master will automatically be elected Normally anew master is elected and started within just a few seconds and during this time no writes can takeplace (the write will throw an exception) A machine that becomes available after being unavailablewill automatically reconnect to the cluster The only time this is not true is when an old master hadchanges that did not get replicated to any other machine If the new master is elected and performschanges before the old master recovers there will two different versions of the data The old masterwill not be able to attach itself to the cluster and will require maintenance (replace the wrong versionof the data with the one running in the cluster)

All this can be summarized as

bull Slaves can handle write transactions

bull Updates to slaves are eventual consistent

bull Neo4j HA is fault tolerant and (depending on ZooKeeper setup) can continue to operate from Xmachines down to a single machine

bull Slaves will be automatically synchronized with the master on a write operation

bull If the master fails a new master will be elected automatically

bull Machines will be reconnected automatically to the cluster whenever the issue that caused the outage(network maintenance) is resolved

bull Transactions are atomic consistent and durable but eventually propagated out to other slaves

bull If the master goes down any running write transaction will be rolled back and during masterelection no write can take place

bull Reads are highly available

Chapter 10 Operations

This chapter describes how to maintain a Neo4j installation This includes topics such as backing upthe database and monitoring the health of the database as well as diagnosing issues

Operations

101 Backup

NoteThe Backup features are only available in the Neo4j Enterprise Edition

Backups are performed over the network live from a running graph database onto a local copy Thereare two types of backup full and incremental

A full backup copies the database files without acquiring any locks allowing for continued operationson the target instance This of course means that while copying transactions will continue and thestore will change For this reason the transaction that was running when the backup operation startedis noted and when the copy operation completes all transactions from the latter down to the onehappening at the end of the copy are replayed on the backup files This ensures that the backed up datarepresent a consistent and up-to-date snapshot of the database storage

In contrast incremental backup does not copy store files - instead it copies the logs of the transactionsthat have taken place since the last full or incremental backup which are then replayed over anexisting backup store This makes incremental backups far more efficient that doing full backupsevery time but they also require that a full backup has taken place before they are executed

Regardless of the mode a backup is created the resulting files represent a consistent database snapshotand they can be used to boot up a Neo4j instance

The database to be backed up is specified using a URI with syntax

ltrunning modegtlthostgt[port]lthostgt[port]

Running mode must be defined and is either single for non-HA or ha for HA clusters Thelthostgt[port] part points to a host running the database on port port if not the default The additionalhostport arguments are useful for passing multiple ZooKeeper instances

ImportantBackups can only be performed on databases which have the configuration parameterenable_online_backup=true set That will make the backup service available on thedefault port (6362) To enable the backup service on a different port use for exampleenable_online_backup=port=9999 instead

1011 Embedded and ServerTo perform a backup from a running embedded or server database run

Performing a full backup

neo4j-backup -full -from single192168134 -to mntbackupneo4j-backup

Performing an incremental backup

neo4j-backup -incremental -from single192168134 -to mntbackupneo4j-backup

Performing an incremental backup where the service is registered on a custom port

1012 High AvailabilityTo perform a backup on an HA cluster you specify one or more ZooKeeper services managing thatcluster

Performing a full backup from HA cluster specifying two possible ZooKeeper services

neo4j-backup -full -from ha19216811521811921681162181 -to mntbackupneo4j-backup

Operations

Performing an incremental backup from HA cluster specifying only one ZooKeeper service

neo4j-backup -incremental -from ha1921681152181 -to mntbackupneo4j-backup

1013 Restoring Your DataThe Neo4j backups are fully functional databases To use a backup all you need to do replace yourdatabase folder with the backup

Operations

102 SecurityNeo4j in itself does not enforce security on the data level However there are different aspects thatshould be considered when using Neo4j in different scenarios

1021 Securing access to the Neo4j ServerThe Neo4j server currently does not enforce security on the REST access layer This should be takencare of by external means We strongly recommend to front a running Neo4j Server with a proxy likeApache mod_proxy 1 This provides a number of advantages

bull Control access to the Neo4j server to specific IP addresses URL patterns and IP ranges This can beused to make for instance only the dbdata namespace accessible to non-local clients while the dbadmin URLs only respond to a specific IP address

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

bull Run Neo4j Server as a non-root user on a LinuxUnix system on a port lt 1000 (eg port 80) using

ProxyPass neo4jdbdata httplocalhost7474dbdata

ProxyPassReverse neo4jdbdata httplocalhost7474dbdata

bull Simple load balancing in a clustered environment to load-balance read load using the Apachemod_proxy_balancer 2 plugin

ltProxy balancermyclustergt

BalancerMember http19216815080

ltProxygt

ProxyPass test balancermycluster

1httphttpdapacheorgdocs22modmod_proxyhtml

Operations

103 Monitoring

NoteMost of the monitoring features are only available in the Advanced and Enterprise editionsof Neo4j

In order to be able to continuously get an overview of the health of a Neo4j database there aredifferent levels of monitoring facilities available

1031 JMX

How to connect to a Neo4j instance using JMX and JConsole

First start your embedded database or the Neo4j Server for instance using

$NEO4j_SERVER_HOMEbinneo4j start

Now start JConsole with

$JAVA_HOMEbinjconsole

Connect to the process running your Neo4j database instance

Figure 101 Connecting JConsole to the Neo4j Java process

Now beside the MBeans exposed by the JVM you will see an orgneo4j section in the MBeans tabUnder that you will have access to all the monitoring information exposed by Neo4j

Operations

Figure 102 Neo4j MBeans View

How to connect to the JMX monitoring programmatically

In order to programmatically connect to the Neo4j JMX server there are some convenience methodsin the Neo4j Management component to help you find out the most commonly used monitoringattributes of Neo4j For instance the number of node IDs in use can be obtained with code like

Neo4jManager manager = new Neo4jManager( graphDbgetManagementBean( Kernelclass ) )

long nodeIDsInUse = managergetPrimitivesBeangetNumberOfNodeIdsInUse()

Once you have access to this information you can use it to for instance expose the values to SNMPlthttpenwikipediaorgwikiSimple_Network_Management_Protocolgt or other monitoring systems

Reference of supported JMX MBeans

Table 101 MBeans exposed by the Neo4j Kernel

Name Description

orgneo4jinstance=kernel0name=MemoryMapping

The status of Neo4j memory mapping

orgneo4jinstance=kernel0name=Locking Information about the Neo4j lock status

orgneo4jinstance=kernel0name=Transactions Information about the Neo4j transaction manager

orgneo4jinstance=kernel0name=Cache Information about the caching in Neo4j

orgneo4jinstance=kernel0name=Configuration The configuration parameters used to configureNeo4j

orgneo4jinstance=kernel0name=Primitivecount

Estimates of the numbers of different kinds ofNeo4j primitives

orgneo4jinstance=kernel0name=XAResources

Information about the XA transaction manager

orgneo4jinstance=kernel0name=Store filesizes

Information about the sizes of the different partsof the Neo4j graph store

orgneo4jinstance=kernel0name=Kernel Information about the Neo4j kernel

orgneo4jinstance=kernel0name=HighAvailability

Information an High Availability cluster ifenabled

Operations

Table 102 MBean Memory Mapping

Attribute Description Type

MemoryPools Get information about each pool of memorymapped regions from store files withmemory mapping enabled

String

Table 103 MBean Locking

NumberOfAdvertedDeadlocks The number of lock sequences that wouldhave lead to a deadlock situation that Neo4jhas detected and adverted (by throwingDeadlockDetectedException)

Integer

Table 104 MBean Transactions

NumberOfOpenTransactions The number of currently open transactions Integer

PeakNumberOfConcurrentTransactions The highest number of transactions everopened concurrently

Integer

NumberOfOpenedTransactions The total number started transactions Integer

NumberOfCommittedTransactions The total number of committed transactionss Integer

Table 105 MBean Cache

CacheType The type of cache used by Neo4j String

NodeCacheSize The number of Nodes currently in cache Integer

RelationshipCacheSize The number of Relationships currently incache

Integer

clear() clear all caches functionvoid

Table 106 MBean Configuration

store_dir Relative path for where the Neo4j storagedirectory is located

String

rebuild_idgenerators_fast Use a quick approach for rebuilding the IDgenerators This give quicker recovery timebut will limit the ability to reuse the space ofdeleted entities

String

logical_log Relative path for where the Neo4j logicallog is located

String

neostore propertystore db index

keys mapped_memory

The size to allocate for memory mapping thestore for property key strings

String

Operations

neostore propertystore db strings

mapped_memory

The size to allocate for memory mapping thestring property store

String

neostore propertystore db arrays

mapped_memory

The size to allocate for memory mapping thearray property store

String

neo_store Relative path for where the Neo4j storageinformation file is located

String

neostore relationshipstore db

mapped_memory

The size to allocate for memory mapping therelationship store

String

mapped_memory

The size to allocate for memory mapping thestore for property key indexes

String

create Configuration attribute String

enable_remote_shell Enable a remote shell server which shellclients can log in to

String

mapped_memory

The size to allocate for memory mapping theproperty value store

Integer

neostore nodestore db mapped_memory The size to allocate for memory mapping thenode store

String

dir Configuration attribute String

Table 107 MBean Primitive count

NumberOfNodeIdsInUse An estimation of the number of nodes usedin this Neo4j instance

Integer

NumberOfRelationshipIdsInUse An estimation of the number of relationshipsused in this Neo4j instance

Integer

NumberOfPropertyIdsInUse An estimation of the number of propertiesused in this Neo4j instance

Integer

NumberOfRelationshipTypeIdsInUse The number of relationship types used inthis Neo4j instance

Integer

Table 108 MBean XA Resources

XaResources Information about all XA resourcesmanaged by the transaction manager

String

Table 109 MBean Store file sizes

TotalStoreSize The total disk space used by this Neo4jinstance in bytes

Integer

LogicalLogSize The amount of disk space used by thecurrent Neo4j logical log in bytes

Integer

Operations

ArrayStoreSize The amount of disk space used to store arrayproperties in bytes

Integer

NodeStoreSize The amount of disk space used to storenodes in bytes

Integer

PropertyStoreSize The amount of disk space used to storeproperties (excluding string values and arrayvalues) in bytes

Integer

RelationshipStoreSize The amount of disk space used to storerelationships in bytes

Integer

StringStoreSize The amount of disk space used to storestring properties in bytes

Integer

Table 1010 MBean Kernel

ReadOnly Whether this is a read only instance boolean

MBeanQuery An ObjectName that can be used as a queryfor getting all management beans for thisNeo4j instance

String

KernelStartTime The time from which this Neo4j instancewas in operational mode

StoreCreationDate The time when this Neo4j graph store wascreated

StoreId An identifier that uniquely identifies thisNeo4j graph store

String

StoreLogVersion The current version of the Neo4j storelogical log

String

KernelVersion The version of Neo4j String

StoreDirectory The location where the Neo4j store islocated

String

Table 1011 MBean High Availability

MachineId The cluster machine id of this instance String

Master True if this Neo4j instance is currentlyMaster in the cluster

boolean

ConnectedSlaves A list of conencted slaves in this cluster String

InstancesInCluster Information about the other Neo4j instancesin this HA cluster

String

Part II Tutorials

Chapter 11 Graph Database Concepts

Graph Database Concepts

111 What is a Graph DatabaseA graph database stores data in a graph the most generic of data structures capable of elegantlyrepresenting any kind of data in a highly accessible way Letrsquos follow along some graphs using themto express graph concepts Wersquoll ldquoreadrdquo a graph by following arrows around the diagram to formsentences

1111 A Graph contains Nodes and RelationshipsldquoA Graph mdashrecords data inndashgt Nodes mdashwhich havendashgt Propertiesrdquo

The simplest possible graph is a single Node a record that has named values referred to as PropertiesA Node could start with a single Property and grow to a few million though that can get a littleawkward At some point it makes sense to distribute the data into multiple nodes organized withexplicit Relationships

records data in Relat ionships

records data in

Propert ies

organize

1112 Relationships organize the GraphldquoNodes mdashare organized byndashgt Relationships mdashwhich also havendashgt Propertiesrdquo

Relationships organize Nodes into arbitrary structures allowing a Graph to resemble a List a Treea Map or a compound Entity ndash any of which can be combined into yet more complex richly inter-connected structures

1113 Query a Graph with a TraversalldquoA Traversal mdashnavigatesndashgt a Graph it mdashidentifiesndashgt Paths mdashwhich orderndashgt Nodesrdquo

A Traversal is how you query a Graph navigating from starting Nodes to related Nodes according toan algorithm finding answers to questions like ldquowhat music do my friends like that I donrsquot yet ownrdquoor ldquoif this power supply goes down what web services are affectedrdquo

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

records data in order

1114 Indexes look-up Nodes or RelationshipsldquoAn Index mdashmaps fromndashgt Properties mdashto eitherndashgt Nodes or Relationshipsrdquo

Often you want to find a specific Node or Relationship according to a Property it has Rather thantraversing the entire graph use an Index to perform a look-up for questions like ldquofind the Account forusername master-of-graphsrdquo

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

1115 Neo4j is a Graph DatabaseldquoA Graph Database mdashmanages andashgt Graph and mdashalso manages relatedndashgt Indexesrdquo

Neo4j is a commercially supported open-source graph database It was designed and built from theground-up to be a reliable database optimized for graph structures instead of tables Working withNeo4j your application gets all the expressiveness of a graph with all the dependability you expectout of a database

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

112 Comparing Database ModelsA Graph Database stores data structured in the Nodes and Relationships of a graph How does thiscompare to other persistence models Because a graph is a generic structure letrsquos compare how a fewmodels would look in a graph

1121 A Graph Database transforms a RDBMSTopple the stacks of records in a relational database while keeping all the relationships and yoursquoll seea graph Where an RDBMS is optimized for aggregated data Neo4j is optimized for highly connecteddata

Figure 111 RDBMS

Figure 112 Graph Database as RDBMS

B3B5 B7

C1 C2C3

1122 A Graph Database elaborates a Key-Value StoreA Key-Value model is great for lookups of simple values or lists When the values are themselvesinterconnected yoursquove got a graph Neo4j lets you elaborate the simple data structures into morecomplex interconnected data

Figure 113 Key-Value Store

Figure 114 Graph Database as Key-Value Store

1123 A Graph Database relates Column-FamilyColumn Family (BigTable-style) databases are an evolution of key-value using families to allowgrouping of rows Stored in a graph the families could become hierarchical and the relationshipsamong data becomes explicit

1124 A Graph Database navigates a Document StoreThe container hierarchy of a document database accommodates nice schema-free data that can easilybe represented as a tree Which is of course a graph Refer to other documents (or document elements)within that tree and you have a more expressive representation of the same data When in Neo4j thoserelationships are easily navigable

Figure 115 Document Store

V1D2S2 V2V3V4D1S1

Figure 116 Graph Database as Document Store

S1D2 S2S3

113 The Neo4j Graph DatabaseThis chapter will introduce more details on the data model and behavior of Neo4j

1131 RelationshipsRelationships between nodes are a key part of a graph database They allow for finding related data

A Relat ionship

Start node

End node

Relat ionship type

uniquely ident ified by

A relationship connects two nodes and is guaranteed to have valid start and end nodes

Start node End noderelat ionship

As relationships are always directed they can be viewed as outgoing or incoming relative to a nodewhich is useful when traversing the graph

Nodeincom ing relat ionship outgoing relat ionship

Relationships are equally well traversed in either direction This means that there is no need to addduplicate relationships in the opposite direction (with regard to traversal or performance)

While relationships always have a direction you can ignore the direction where it is not useful in yourapplication

Note that a node can have relationships to itself as well

Node loop

To further enhance graph traversal all relationships have a relationship type The following exampleshows a simple social network with two relationship types

follows follows

William

blocks

follows

Table 111 Using relationship direction and type

What How

get who a person follows outgoing follows relationships depth one

get the followers of a person incoming follows relationships depth one

get who a person blocks outgoing blocks relationships depth one

get who a person is blocked by incoming blocks relationships depth one

This example is a simple model of a file system which includes symbolic links

sym bolic link nam e E

Depending on what you are looking for you will use the direction and type of relationships duringtraversal

What How

get the full path of a file incoming file relationships

get all paths for a file incoming file and symbolic link relationships

get all files in a directory outgoing file and symbolic link relationshipsstop at depth one

get all files in a directory excluding symboliclinks

outgoing file relationships stop at depth one

get all files in a directory recursively outgoing file and symbolic link relationships

1132 PropertiesProperties are key-value pairs where the key is a string Property values can be either a primitive or anarray of one primitive type For example String int and int[] values are valid for properties

Notenull is not a valid property value Nulls can instead be modeled by the absence of a key

A Property

Prim it ive

boolean

double

St ring

is acan be acan be an array of

Table 112 Property value types

Type Description Value range

boolean truefalse

byte 8-bit integer -128 to 127 inclusive

short 16-bit integer -32768 to 32767 inclusive

int 32-bit integer -2147483648 to 2147483647 inclusive

long 64-bit integer -9223372036854775808 to9223372036854775807 inclusive

float 32-bit IEEE 754 floating-point number

double 64-bit IEEE 754 floating-point number

char 16-bit unsigned integers representingUnicode characters

u0000 to uffff (0 to 65535)

String sequence of Unicode characters

For further details on floatdouble values see Java Language Specification lthttpjavasuncomdocsbooksjlsthird_editionhtmltypesValueshtml423gt

Chapter 12 Using Neo4j embedded in Java applications

Using Neo4j embedded in Java applications

121 Include Neo4j in your projectAfter selecting the appropriate edition for your platform embed Neo4j in your Java application byincluding the Neo4j library jars in your build

1211 Add Neo4j to the build pathGet the Neo4j libraries from one of these sources

bull Extract a Neo4j download lthttpneo4jorgdownloadgt ziptarball and use the jar files found inthe lib directory

bull Use the jar files available from Maven Central Repository lthttpsearchmavenorgsearch|ga|1|g3A22orgneo4j22gt

Add the jar files to your project

JDK toolsAppend to -classpath

Eclipse

bull Right-click on the project and then go Build Path ndashgt Configure Build Path In the dialogchoose Add External JARs browse to the Neo4j lib directory and select all of the jar files

bull Another option is to use User Libraries lthttphelpeclipseorgheliosindexjsptopic=orgeclipsejdtdocuserreferencepreferencesjavabuildpathref-preferences-user-librarieshtmgt

IntelliJ IDEASee Libraries Global Libraries and the Configure Library dialog lthttpwwwjetbrainscomideawebhelplibraries-global-libraries-and-the-configure-library-dialoghtmlgt

NetBeans

bull Right-click on the Libraries node of the project choose Add JARFolder browse to the Neo4jlib directory and select all of the jar files

bull You can also handle libraries from the proejct node see Managing a Projectrsquos Classpath lthttpnetbeansorgkbdocsjavaproject-setuphtmlprojects-classpathgt

1212 Add Neo4j as a dependencyFor an overview of the main Neo4j artifacts see Table 12 ldquoNeo4j editionsrdquo The artifacts listed thereare top-level artifacts that will transitively include the actual Neo4j implementation You can either gowith the top-level artifact or include the individual components directly The examples included hereuse the top-level artifact approach

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

Where $neo4j-version is the intended version and the artifactId is found in Table 12 ldquoNeo4jeditionsrdquo

IvyMake sure to resolve dependencies from Maven Central for example using this configuration in yourivysettingsxml file

ltivysettingsgt

ltsettings defaultResolver=maingt

ltresolversgt

ltchain name=maingt

ltfilesystem name=localgt

ltartifact pattern=$ivysettingsdirrepository[artifact]-[revision][ext] gt

ltfilesystemgt

ltibiblio name=maven_central root=httprepo1mavenorgmaven2 m2compatible=truegt

ltchaingt

ltresolversgt

ltivysettingsgt

With that in place you can add Neo4j to the mix by having something along these lines to your ivyxmlfile

ltdependenciesgt

ltdependency org=orgneo4j name=neo4j rev=$neo4j-versiongt

ltdependenciesgt

Where $neo4j-version is the intended version and the name is found in Table 12 ldquoNeo4jeditionsrdquo

122 Hello worldCreate and access nodes and relationships

To begin with we define the relationship types we want to use

private static enum ExampleRelationshipTypes implements RelationshipType

EXAMPLE

The next step is to start the database server

GraphDatabaseService graphDb = new EmbeddedGraphDatabase( DB_PATH )

registerShutdownHook( graphDb )

As seen we register a shutdown hook that will make sure the database shuts down when the JVMexits Now itrsquos time to interact with the database

Encapsulate operations in a transaction

Node firstNode = graphDbcreateNode()

firstNodesetProperty( NAME_KEY Hello )

Node secondNode = graphDbcreateNode()

secondNodesetProperty( NAME_KEY World )

firstNodecreateRelationshipTo( secondNode

ExampleRelationshipTypesEXAMPLE )

String greeting = firstNodegetProperty( NAME_KEY ) +

+ secondNodegetProperty( NAME_KEY )

Systemoutprintln( greeting )

At this point this is how the database looks

In this case wersquoll remove the data before committing

lets remove the data before committing

firstNodegetSingleRelationship( ExampleRelationshipTypesEXAMPLE

DirectionOUTGOING )delete()

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

Finally shut down the database server when the application finishes

graphDbshutdown()

Full source code EmbeddedNeo4jjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrcmainjavaorgneo4jexamplesEmbeddedNeo4jjavagt

123 User database with indexYou have a user database and want to retrieve users by name To begin with this is the structure ofthe database we want to create

Figure 121 Node space view of users

That is the reference node is connected to a users-reference node to which all users are connected

private static enum RelTypes implements RelationshipType

USERS_REFERENCE

Then we have created two helper methods to handle user names and adding users to the database

private static String idToUserName( final int id )

return user + id + neo4jorg

private static Node createAndIndexUser( final String username )

Node node = graphDbcreateNode()

nodesetProperty( USERNAME_KEY username )

nodeIndexadd( node USERNAME_KEY username )

return node

graphDb = new EmbeddedGraphDatabase( DB_PATH )

nodeIndex = graphDbindex()forNodes( nodes )

registerShutdownHook()

Itrsquos time to add the users

Create users sub reference node (see design guidelines on

httpwikineo4jorg )

Node usersReferenceNode = graphDbcreateNode()

graphDbgetReferenceNode()createRelationshipTo(

usersReferenceNode RelTypesUSERS_REFERENCE )

Create some users and index their names with the IndexService

for ( int id = 0 id lt 100 id++ )

Node userNode = createAndIndexUser( idToUserName( id ) )

usersReferenceNodecreateRelationshipTo( userNode

RelTypesUSER )

And herersquos how to find a user by Id

int idToFind = 45

Node foundUser = nodeIndexget( USERNAME_KEY

idToUserName( idToFind ) )getSingle()

Systemoutprintln( The username of user + idToFind + is

+ foundUsergetProperty( USERNAME_KEY ) )

Full source code EmbeddedNeo4jWithIndexingjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrcmainjavaorgneo4jexamplesEmbeddedNeo4jWithIndexingjavagt

124 Traversal

1241 The MatrixThis is the first node space we want to traverse into

Figure 122 Matrix node space view

Friends and friends of friends

private static Traverser getFriends( final Node person )

return persontraverse( OrderBREADTH_FIRST

StopEvaluatorEND_OF_GRAPH

ReturnableEvaluatorALL_BUT_START_NODE RelTypesKNOWS

DirectionOUTGOING )

Letrsquos perform the actual traversal and print the results

Traverser friendsTraverser = getFriends( neoNode )

int numberOfFriends = 0

for ( Node friendNode friendsTraverser )

Systemoutprintln( At depth

+ friendsTraversercurrentPosition()

depth() + =gt

+ friendNodegetProperty( name ) )

Who coded the Matrix

private static Traverser findHackers( final Node startNode )

return startNodetraverse( OrderBREADTH_FIRST

StopEvaluatorEND_OF_GRAPH new ReturnableEvaluator()

Override

public boolean isReturnableNode(

final TraversalPosition currentPos )

return currentPosisStartNode()

ampamp currentPoslastRelationshipTraversed()

isType( RelTypesCODED_BY )

RelTypesCODED_BY DirectionOUTGOING RelTypesKNOWS

DirectionOUTGOING )

Print out the result

Traverser traverser = findHackers( getNeoNode() )

int numberOfHackers = 0

for ( Node hackerNode traverser )

Systemoutprintln( At depth + traversercurrentPosition()

depth() + =gt + hackerNodegetProperty( name ) )

Full source code MatrixTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesMatrixTestjavagt

1242 User rolesHere we have users assigned to groups and groups containing other groups This is the full nodespace of our example

Figure 123 User roles node space view

Get the admins

Node admins = getGroupByName( Admins )

Traverser traverser = adminstraverse(

TraverserOrderBREADTH_FIRST StopEvaluatorEND_OF_GRAPH

ReturnableEvaluatorALL_BUT_START_NODE RoleRelsPART_OF

DirectionINCOMING RoleRelsMEMBER_OF DirectionINCOMING )

for ( Node part traverser )

Systemoutprintln( partgetProperty( NAME )

+ ( traversercurrentPosition()depth() - 1 ) )

Get the group memberships of a user

Node jale = getUserByName( Jale )

Traverser traverser = jaletraverse( TraverserOrderDEPTH_FIRST

ReturnableEvaluatorALL_BUT_START_NODE RoleRelsMEMBER_OF

DirectionOUTGOING RoleRelsPART_OF DirectionOUTGOING )

for ( Node membership traverser )

Systemoutprintln( membershipgetProperty( NAME )

Get all groups

Node referenceNode = graphDbgetReferenceNode()

Traverser traverser = referenceNodetraverse(

ReturnableEvaluatorALL_BUT_START_NODE RoleRelsROOT

DirectionINCOMING RoleRelsPART_OF DirectionINCOMING )

for ( Node group traverser )

Systemoutprintln( groupgetProperty( NAME ) )

Get all members of all groups

new ReturnableEvaluator()

Override

TraversalPosition currentPos )

if ( currentPosisStartNode() )

return false

Relationship rel = currentPoslastRelationshipTraversed()

return relisType( RoleRelsMEMBER_OF )

RoleRelsROOT

DirectionINCOMING RoleRelsPART_OF DirectionINCOMING

RoleRelsMEMBER_OF DirectionINCOMING )

Full source code RolesTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesRolesTestjavagt

1243 New traversal framework

NoteThe following examples use a new experimental traversal API It shares the underlyingimplementation with the old traversal API so performance-wise they should be equalHowever expect the new API to evolve and thus undergo changes

The Matrix

The traversals from the Matrix example above this time using the new traversal API

TraversalDescription td = Traversaldescription()

breadthFirst()

relationships( RelTypesKNOWS DirectionOUTGOING )

evaluator( EvaluatorsexcludeStartPosition() )

return tdtraverse( person )

for ( Path friendPath friendsTraverser )

Systemoutprintln( At depth + friendPathlength() + =gt

+ friendPathendNode()

getProperty( name ) )

breadthFirst()

relationships( RelTypesCODED_BY DirectionOUTGOING )

evaluator(

EvaluatorsreturnWhereLastRelationshipTypeIs( RelTypesCODED_BY ) )

return tdtraverse( startNode )

for ( Path hackerPath traverser )

Systemoutprintln( At depth + hackerPathlength() + =gt

+ hackerPathendNode()

Full source code MatrixNewTravTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesMatrixNewTravTestjavagt

User roles

The traversals from the User roles example above this time using the new traversal API

Get the admins

breadthFirst()

relationships( RoleRelsPART_OF DirectionINCOMING )

relationships( RoleRelsMEMBER_OF DirectionINCOMING )

for ( Path path tdtraverse( admins ) )

Node part = pathendNode()

Systemoutprintln( partgetProperty( NAME ) +

+ ( pathlength() - 1 ) )

depthFirst()

relationships( RoleRelsMEMBER_OF DirectionOUTGOING )

relationships( RoleRelsPART_OF DirectionOUTGOING )

for ( Path path tdtraverse( jale ) )

Node membership = pathendNode()

Systemoutprintln( membershipgetProperty( NAME ) +

Get all groups

breadthFirst()

relationships( RoleRelsROOT DirectionINCOMING )

for ( Node group tdtraverse( referenceNode )

nodes() )

breadthFirst()

evaluator(

EvaluatorspruneWhereLastRelationshipTypeIs( RoleRelsMEMBER_OF ) )

for ( Node group tdtraverse( referenceNode )nodes() )

Full source code RolesNewTravTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesRolesNewTravTestjavagt

Walking an ordered path

This example shows how to use a path context holding a representation of a path

Create a toy graph

Node A = dbcreateNode()

Node B = dbcreateNode()

Node C = dbcreateNode()

Node D = dbcreateNode()

AcreateRelationshipTo( B REL1 )

BcreateRelationshipTo( C REL2 )

CcreateRelationshipTo( D REL3 )

AcreateRelationshipTo( C REL2 )

Figure 124 The example graph

Now the order of relationships (REL1 ndashgt REL2 ndashgt REL3) is stored in an ArrayList Upon traversalthe Evaluator can check against it to ensure that only paths are included and returned that have thepredefined order of relationships

Walk the path

final ArrayListltRelationshipTypegt orderedPathContext = new ArrayListltRelationshipTypegt()

orderedPathContextadd( REL1 )

orderedPathContextadd( withName( REL2 ) )

TraversalDescription td = Traversaldescription()evaluator(

new Evaluator()

Override

public Evaluation evaluate( final Path path )

if ( pathlength() == 0 )

return EvaluationEXCLUDE_AND_CONTINUE

String currentName = pathlastRelationship()getType()name()

String relationshipType = orderedPathContextget(

pathlength() - 1 )name()

if ( pathlength() == orderedPathContextsize() )

if ( currentNameequals( relationshipType ) )

return EvaluationINCLUDE_AND_PRUNE

return EvaluationEXCLUDE_AND_PRUNE

Traverser t = tdtraverse( dbgetNodeById( 1 ) )

for ( Path path t )

Systemoutprintln( path )

Full source code OrderedPathTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesorderedpathOrderedPathTestjavagt

1244 Social network

NoteThe following example uses the new experimental traversal API

Social networks (know as social graphs out on the web) are natural to model with a graph Thisexample shows a very simple social model that connects friends and keeps track of status updates

Simple social model

Figure 125 Social network data model

The data model for a social network is pretty simple Persons with names and StatusUpdates withtimestamped text These entities are then connected by specific relationships

bull Person

bull friend relates two distinct Person instances (no self-reference)

bull status connects to the most recent StatusUpdate

bull StatusUpdate

bull next points to the next StatusUpdate in the chain which was posted before the current one

Status graph instance

The StatusUpdate list for a Person is a linked list The head of the list (the most recent status) isfound by following status Each subsequent StatusUpdate is connected by next

Herersquos an example where Andreas Kollegger micro-blogged his way to work in the morning

Figure 126 Andreas Kolleggers status updates

To read the status updates we can create a traversal like so

TraversalDescription traversal = Traversaldescription()

depthFirst()

relationships( NEXT )

filter( TraversalreturnAll() )

This gives us a traverser that will start at one StatusUpdate and will follow the chain of updatesuntil they run out Traversers are lazy loading so itrsquos performant even when dealing with thousands ofstatuses - they are not loaded until we actually consume them

Activity streamOnce we have friends and they have status messages we might want to read our friends statusmessages in reverse time order - latest first To do this we go through these steps

1 Gather all friendrsquos status update iterators in a list - latest date first2 Sort the list3 Return the first item in the list4 If the first iterator is exhausted remove it from the list Otherwise get the next item in that iterator5 Go to step 2 until there are no iterators left in the list

Animated the sequence looks like this lthttpwwwslidesharenetsystaypattern-activity-streamgt

The code looks like

PositionedIteratorltStatusUpdategt first = statusesget(0)

StatusUpdate returnVal = firstcurrent()

if ( firsthasNext() )

statusesremove( 0 )

firstnext()

sort()

return returnVal

Full source code socnet lthttpsgithubcomneo4jcommunitytree14M06embedded-examplessrcmainjavaorgneo4jexamplessocnetgt

125 Domain entitiesThis page demonstrates one way to handle domain entities when using Neo4j The principle at use isto wrap the entities around a node (the same approach can be used with relationships as well)

First off store the node and make it accessible inside the package

private final Node underlyingNode

Person( Node personNode )

thisunderlyingNode = personNode

protected Node getUnderlyingNode()

return underlyingNode

Delegate attributes to the node

public String getName()

return (String)underlyingNodegetProperty( NAME )

Make sure to override these methods

Override

public int hashCode()

return underlyingNodehashCode()

Override

public boolean equals( Object o )

return o instanceof Person ampamp

underlyingNodeequals( ( (Person)o )getUnderlyingNode() )

Override

public String toString()

return Person[ + getName() + ]

Full source code Personjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrcmainjavaorgneo4jexamplessocnetPersonjavagt

126 Graph Algorithm examplesCalculating the shortest path (least number of relationships) between two nodes

Node startNode = graphDbcreateNode()

Node middleNode1 = graphDbcreateNode()

Node endNode = graphDbcreateNode()

createRelationshipsBetween( startNode middleNode1 endNode )

createRelationshipsBetween( startNode middleNode2 middleNode3 endNode )

Will find the shortest path between startNode and endNode via

MY_TYPE relationships (in OUTGOING direction) like fex

(startNode)--gt(middleNode1)--gt(endNode)

PathFinderltPathgt finder = GraphAlgoFactoryshortestPath(

TraversalexpanderForTypes( ExampleTypesMY_TYPE DirectionOUTGOING ) 15 )

IterableltPathgt paths = finderfindAllPaths( startNode endNode )

Using Dijkstrarsquos algorithm lthttpenwikipediaorgwikiDijkstra27s_algorithmgt to calculatecheapest path between node A and B where each relationship can have a weight (ie cost) and thepath(s) with least cost are found

PathFinderltWeightedPathgt finder = GraphAlgoFactorydijkstra(

TraversalexpanderForTypes( ExampleTypesMY_TYPE DirectionBOTH ) cost )

WeightedPath path = finderfindSinglePath( nodeA nodeB )

Get the weight for the found path

pathweight()

Using A lthttpenwikipediaorgwikiA_search_algorithmgt to calculate the cheapest path betweennode A and B where cheapest is for example the path in a network of roads which has the shortestlength between node A and B Herersquos our example graph

Node nodeA = createNode( name A x 0d y 0d )

Node nodeB = createNode( name B x 7d y 0d )

Node nodeC = createNode( name C x 2d y 1d )

Relationship relAB = createRelationship( nodeA nodeC length 2d )

Relationship relBC = createRelationship( nodeC nodeB length 3d )

Relationship relAC = createRelationship( nodeA nodeB length 10d )

EstimateEvaluatorltDoublegt estimateEvaluator = new EstimateEvaluatorltDoublegt()

public Double getCost( final Node node final Node goal )

double dx = (Double) nodegetProperty( x ) - (Double) goalgetProperty( x )

double dy = (Double) nodegetProperty( y ) - (Double) goalgetProperty( y )

double result = Mathsqrt( Mathpow( dx 2 ) + Mathpow( dy 2 ) )

return result

PathFinderltWeightedPathgt astar = GraphAlgoFactoryaStar(

TraversalexpanderForAllTypes()

CommonEvaluatorsdoubleCostEvaluator( length ) estimateEvaluator )

WeightedPath path = astarfindSinglePath( nodeA nodeB )

Full source code PathFindingExamplesTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesPathFindingExamplesTestjavagt

127 Reading a management attributeReading a management attribute

The EmbeddedGraphDatabase lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jkernelEmbeddedGraphDatabasehtmlgt class includes a convenience method lthttpcomponentsneo4jorgneo4j14M06apidocsorgneo4jkernelEmbeddedGraphDatabasehtmlgetManagementBean28javalangClass29gt to get instances of Neo4j management beans The common JMX servicecan be used as well but from your code you probably rather want to use the approach outlined here

This example shows how to get the start time of a database

private static Date getStartTimeFromManagementBean(

GraphDatabaseService graphDbService )

use EmbeddedGraphDatabase to access management beans

EmbeddedGraphDatabase graphDb = (EmbeddedGraphDatabase) graphDbService

Kernel kernel = graphDbgetManagementBean( Kernelclass )

Date startTime = kernelgetKernelStartTime()

return startTime

Depending on which Neo4j edition you are using different sets of management beans are available

bull For all editions see the orgneo4jjmx lthttpcomponentsneo4jorgneo4j-jmx14M06apidocsorgneo4jjmxpackage-summaryhtmlgt package

bull For the Advanced and Enterprise editions see the orgneo4jmanagement lthttpcomponentsneo4jorgneo4j-management14M06apidocsorgneo4jmanagementpackage-summaryhtmlgt package as well

Full source code JmxTestjava lthttpsgithubcomneo4jcommunityblob14M06embedded-examplessrctestjavaorgneo4jexamplesJmxTestjavagt

Part III Tools

Chapter 13 Web Administration

The Neo4j Web Administration is the primary user interface for Neo4j With it you can

bull monitor the Neo4j Server

bull manipulate and browse data

bull interact with the database via various consoles

bull view raw data management objects (JMX MBeans)

Web Administration

131 Dashboard tabThe Dashboard tab provides an overview of a running Neo4j instance

Figure 131 Web Administration Dashboard

1311 Entity chartThe charts show entity counts over time node relationship and properties

Figure 132 Entity charting

1312 Status monitoringBelow the entity chart is a collection of status panels displaying current resource usage

Figure 133 Status indicator panels

Web Administration

132 Data tabUse the Data tab to browse add or modify nodes relationships and their properties

Figure 134 Browsing and manipulating data

Figure 135 Editing properties

Web Administration

133 Console tabThe Console tab gives

bull scripting access to the database via the Gremlin lthttpgremlintinkerpopcomgt scripting engine

bull query access via Cypher

bull HTTP access via the HTTP console

Figure 136 Traverse data with Gremlin

Figure 137 Query data with Cypher

Web Administration

Figure 138 Interact over HTTP

Web Administration

134 The Server Info tabThe Server Info tab provides raw access to all available management objects (see Section 103ldquoMonitoringrdquo for details)

Figure 139 JMX Attributes

Chapter 14 Neo4j Shell

Neo4j shell is a command-line shell for browsing the graph much like how the Unix shell along withcommands like cd ls and pwd can be used to browse your local file system It consists of two parts

bull a lightweight client that sends commands via RMI and

bull a server that processes those commands and sends the result back to the client

Itrsquos a nice tool for development and debugging This guide will show you how to get it going

Neo4j Shell

141 Starting the shellWhen used together with Neo4j started as a server simply issue the following at the command line

binneo4j-shell

For the full list of options see the reference in the Shell manual page

To connect to a running Neo4j database use Section 1414 ldquoRead-only moderdquo for local databasesand see Section 1411 ldquoEnabling the shell serverrdquo for remote databases

You need to make sure that the shell jar file is on the classpath when you start up your Neo4j instance

1411 Enabling the shell serverShell is enabled from the configuration of the Neo4j kernel see Section 52 ldquoServer ConfigurationrdquoHerersquos some sample configurations

Using default values

enable_remote_shell = true

or specify custom port use default values for the others

enable_remote_shell = port=1234

When using the Neo4j server see Section 52 ldquoServer Configurationrdquo for how to add configurationsettings in that case

There are two ways to start the shell either by connecting to a remote shell server or by pointing it toa Neo4j store path

1412 Connecting to a shell serverTo start the shell and connect to a running server run

neo4j-shell

Alternatively supply -port and -name options depending on how the remote shell server was enabledThen yoursquoll get the shell prompt like this

neo4j-sh (0)$

1413 Pointing the shell to a pathTo start the shell by just pointing it to a Neo4j store path you run the shell jar file Given that the rightneo4j-kernel-ltversiongtjar and jta jar files are in the same path as your neo4j-shell-ltversiongtjar fileyou run it with

$ neo4j-shell -path pathtoneo4j-db

1414 Read-only modeBy issuing the -readonly switch when starting the shell with a store path changes cannot be made tothe database during the session

$ neo4j-shell -readonly -path pathtoneo4j-db

1415 Run a command and then exitIt is possible to tell the shell to just start execute a command and then exit This opens up for uses ofbackground jobs and also handling of huge output of fex an ls command where you then could pipethe output to less or another reader of your choice or even to a file So some examples of usage

$ neo4j-shell -c cd -a 24 ampamp set name Mattias

Neo4j Shell

$ neo4j-shell -c trav -r KNOWS | less

Neo4j Shell

142 Passing options and argumentsPassing options and arguments to your commands is very similar to many CLI commands in an nixenvironment Options are prefixed with a - and can contain one or more options Some options expecta value to be associated with it Arguments are string values which arenrsquot prefixed with - Letrsquos lookat ls as an example

ls -r -f KNOWSout -v 12345 will make a verbose listing of node 12345s outgoing relationshipsof type KNOWS The node id 12345 is an argument to ls which tells it to do the listing on that nodeinstead of the current node (see pwd command) However a shorter version of this can be written

ls -rfv KNOWSout 12345 Here all three options are written together after a single - prefix Eventhough f is in the middle it gets associated with the KNOWSout value The reason for this is that the lscommand doesnrsquot expect any values associated with the r or v options So it can infer the right valuesfor the rights options

Neo4j Shell

143 Enum optionsSome options expects a value which is one of the values in an enum fex direction part ofrelationship type filtering where therersquos INCOMING OUTGOING and BOTH All such values can besupplied in an easier way Itrsquos enough that you write the start of the value and the interpreter will findwhat you really meant Fex out in i or even INCOMING

Neo4j Shell

144 FiltersSome commands makes use of filters for varying purposes Fex -f in ls and in trav A filter issupplied as a json lthttpwwwjsonorggt object (w or wo the surrounding brackets Both keysand values can contain regular expressions for a more flexible matching An example of a filter couldbe urlhttpneo4jnameNeo4j The filter option is also accompanied by the options -i and -l which stands for ignore case (ignore casing of the characters) and loose matching (itrsquosconsidered a match even if the filter value just matches a part of the compared value not necessarilythe entire value) So for a case-insensitive loose filter you can supply a filter with -f -i -l or -filfor short

Neo4j Shell

145 Node titlesTo make it easier to navigate your graph the shell can display a title for each node fex in ls -r Itwill display the relationships as well as the nodes on the other side of the relationships The title isdisplayed together with each node and its best suited property value from a list of property keys

If yoursquore standing on a node which has two KNOWS relationships to other nodes itrsquod be difficult toknow which friend is which The title feature addresses this by reading a list of property keys andgrabbing the first existing property value of those keys and displays it as a title for the node So youmay specify a list (with or without regular expressions) fex nametitlecaption and the titlefor each node will be the property value of the first existing key in that list The list is defined by theclient (you) using the TITLE_KEYS environment variable and the default being nametitle

Neo4j Shell

146 How to use (individual commands)The shell is modeled after Unix shells like bash that you use to walk around your local file systemIt has some of the same commands like cd and ls When you first start the shell (see instructionsabove) you will get a list of all the available commands Use man ltcommandgt to get more info about aparticular command Some notes

1461 Current noderelationship and pathYou have a current noderelationship and a current path (like a current working directory in bash)that yoursquove traversed so far You start at the reference node lthttpapineo4jorgcurrentorgneo4jgraphdbGraphDatabaseServicehtmlgetReferenceNode()gt and can then cd your way through thegraph (check your current path at any time with the pwd command) cd can be used in different ways

bull cd ltnode-idgt will traverse one relationship to the supplied node id The node must have a directrelationship to the current node

bull cd -a ltnode-idgt will do an absolute path change which means the supplied node doesnrsquot have tohave a direct relationship to the current node

bull cd -r ltrelationship-idgt will traverse to a relationship instead of a node The relationshipmust have the current node as either start or end point To see the relationship ids use the ls -vrcommand on nodes

bull cd -ar ltrelationship-idgt will do an absolute path change which means the relationship can beany relationship in the graph

bull cd will take you back to the reference node where you started in the first placebull cd will traverse back one step to the previous location removing the last path item from your

current path (pwd)bull cd start (only if your current location is a relationship) Traverses to the start node of the

relationshipbull cd end (only if your current location is a relationship) Traverses to the end node of the

relationship

1462 Listing the contents of a noderelationshipList contents of the current noderelationship (or any other node) with the ls command Please notethat it will give an empty output if the current noderelationship has no properties or relationships (forexample in the case of a brand new graph) ls can take a node id as argument as well as filters seeSection 144 ldquoFiltersrdquo and for information about how to specify direction see Section 143 ldquoEnumoptionsrdquo Use man ls for more info

1463 Creating nodes and relationshipsYou create new nodes by connecting them with relationships to the current node For examplemkrel -t A_RELATIONSHIP_TYPE -d OUTGOING -c will create a new node (-c) and draw to it anOUTGOING relationship of type A_RELATIONSHIP_TYPE from the current node If you already have twonodes which yoursquod like to draw a relationship between (without creating a new node) you can do forexample mkrel -t A_RELATIONSHIP_TYPE -d OUTGOING -n ltother-node-idgt and it will justcreate a new relationship between the current node and that other node

1464 Setting renaming and removing propertiesProperty operations are done with the set mv and rm commands These commands operates on thecurrent noderelationship set ltkeygt ltvaluegt with optionally the -t option (for value type) sets aproperty Supports every type of value that Neo4j supports Examples of a property of type int

Neo4j Shell

$ set -t int age 29

And an example of setting a double[] property

$ set -t double[] my_values [1412213]

Example of setting a String property containing a JSON string

mkrel -c -d i -t DOMAIN_OF --np appfoobar

bull rm ltkeygt removes a property

bull mv ltkeygt ltnew-keygt renames a property from one key to another

1465 Deleting nodes and relationshipsDeleting nodes and relationships is done with the rmrel command It focuses on deletion ofrelationships but a node can also be deleted if the deleted relationship leaves the opposite nodestranded (ie it no longer has any relationships drawn to it) and the -d options is supplied See therelationship ids with the ls -rv command

1466 Environment variablesThe shell uses environment variables a-la bash to keep session information such as the current pathand more The commands for this mimics the bash commands export and env For example youcan at anytime issue a export STACKTRACES=true command to set the STACKTRACES environmentvariable to true This will then result in stacktraces being printed if an exception or error shouldoccur List environment variables using env

1467 Executing groovypython scriptsThe shell has support for executing scripts such as Groovy lthttpgroovycodehausorggt andPython lthttpwwwpythonorggt (via Jython lthttpwwwjythonorggt) As of now the scripts(groovy py) must exist on the server side and gets called from a client with for examplegsh --renamePerson 1234 Mathias Mattias --doSomethingElse where the scriptsrenamePersongroovy and doSomethingElsegroovy must exist on the server side in any of the pathsgiven by the GSH_PATH environment variable (defaults to srcsrcscript) This variable is like thejava classpath separated by a The pythonjython scripts can be executed with the jsh in a similarfashion however the scripts have the py extension and the environment variable for the paths isJSH_PATH

When writing the scripts assume that therersquos made available an args variable (a String[]) whichcontains the supplied arguments In the case of the renamePerson example above the array wouldcontain [1234 Mathias Mattias] Also please write your outputs to the out variable suchas outprintln( My tracing text ) so that it will be printed at the shell client instead of theserver

1468 TraverseYou can traverse the graph with the trav command which allows for simple traversing from thecurrent node You can supply which relationship types (w regex matching) and optionally directionas well as property filters for matching nodes In addition to that you can supply a command line toexecute for each match An example trav -o depth -r KNOWSbothHAS_incoming -c ls$n Which means traverse depth first for relationships with type KNOWS disregarding direction andincoming relationships with type matching HAS_ and do a ls ltmatching nodegt for each matchThe node filtering is supplied with the -f option see Section 144 ldquoFiltersrdquo See Section 143 ldquoEnum

Neo4j Shell

optionsrdquo for the traversal order option Even relationship typesdirections are supplied using the sameformat as filters

1469 Query with CypherYou can use Cypher to query the graph For that use the start command

bull start n = (0) return n will give you a listing of the node with ID 0

14610 IndexingItrsquos possible to query and manipulate indexes via the index command Example index -i personsname (will index the name for the current node or relationship in the persons index)

bull -g will do exact lookup in the index and display hits You can supply -c with a command to beexecuted for each hit

bull -q will ask the index a query and display hits You can supply -c with a command to be executedfor each hit

bull --cd will change current location to the hit from the query Itrsquos just a convenience for using the -coption

bull --ls will do a listing of the contents for each hit Itrsquos just a convenience for using the -c option

bull -i will index a key-value pair in an index for the current noderelationship If no value is given theproperty value for that key for the current node is used as value

bull -r will remove a key-value pair (if it exists) from an index for the current noderelationship If novalue is given the property value for that key for the current node is used as value

Neo4j Shell

147 Extending the shell Adding your own commandsOf course the shell is extendable and has a generic core which has nothing to do with Neo4jhellip onlysome of the commands lthttpcomponentsneo4jorgneo4j-shell14M06apidocsorgneo4jshellApphtmlgt do

So you say yoursquod like to start a Neo4j graph database lthttpapineo4jorgcurrentorgneo4jgraphdbGraphDatabaseServicehtmlgt enable the remote shell and add your own apps to it so that your appsand the standard Neo4j apps co-exist side by side Well herersquos an example of how an app could looklike

public class LsRelTypes extends GraphDatabaseApp

Override

protected String exec( AppCommandParser parser Session session Output out )

throws ShellException RemoteException

GraphDatabaseService graphDb = getServer()getDb()

outprintln( Types )

for ( RelationshipType type graphDbgetRelationshipTypes() )

outprintln( typename() )

return null

You make your app discoverable via the Java Service API so in a file eg srcmainresourcesMETA-INFservicesorgneo4jshellApp include orgmydomainMyShellApp

And you could now use it in the shell by typing lsreltypes (its name is based on the class name)

If yoursquod like it to display some nice help information when using the help (or man) app override thegetDescription method for a general description and use addValueType method to add descriptionsabout (and logic to) the options you can supply when using your app

Know that the apps reside server-side so if you have a running server and starts a remote client to itfrom another JVM you canrsquot add your apps on the client

Neo4j Shell

148 An example shell session where are we

Current is (0)

On the current node set the key name to value Jon

set name Jon

send a cypher query

+----------------------+

| Node[0]name-gtJon |

+----------------------+

1 rows 42 ms

make an incoming relationship of type LIKES create the end node with the node properties specified

mkrel -c -d i -t LIKES --np appfoobar

where are we

name =[Jon]

(me) lt-[LIKES]-- (1)

change to the newly created node

list relationships including relationshship id

ls -avr

(me) --[LIKES0]-gt (0)

create one more KNOWS relationship and the end node

mkrel -c -d i -t KNOWS --np nameBob

print current history stack

Current is (1)

(0)--gt(1)

verbose list relationships

ls -avr

(me) lt-[KNOWS1]-- (2)

Part IV Troubleshooting

Chapter 15 Troubleshooting guide

Problem Cause Resolution

OutOfMemoryError Too large top leveltransactions or leakingtransactions not finishedproperly

Split updates into smallertransactions Always makesure transactions are finishedproperly

ResourceAcquisitionFailedExceptionor an error message containing the textldquoThe transaction is marked for rollbackonlyrdquo

Leaked non finishedtransaction tied to the currentthread in state marked forrollback only

Finish transactions properly

DeadlockDetectedException Concurrent updates ofcontended resources ornot finishing transactionsproperly

See Section 34ldquoDeadlocksrdquo

Chapter 16 Community support

Get help from the Neo4j open source community here are some starting points

bull Searchable user mailing list archive lthttpwwwmail-archivecomuserlistsneo4jorginfohtmlgt

bull User mailing list lthttpslistsneo4jorgmailmanlistinfousergt

bull Neo4j wiki lthttpwikineo4jorggt

bull IRC channel ircircfreenodenetneo4j

Appendix A Manpages

The Neo4j Unix manual pages are included on the following pages

Manpages

Nameneo4j mdash Neo4j Server control and management

Synopsisneo4j ltcommandgt

DESCRIPTIONNeo4j is a graph database perfect for working with highly connected data

COMMANDS

consoleStart the server as an application running as a foreground proces Stop the server using CTRL-C

startStart server as daemon running as a background process

stopStops a running daemonized server

restartRestarts the server

statusCurrent running state of the server

installInstalls the server as a platform-appropriate system service

removeUninstalls the system service

infoDisplays configuration information such as the current NEO4J_HOME and CLASSPATH

Usage - WindowsNeo4jbat

Double-clicking on the Neo4jbat script will start the server in a console To quit just press control-C in the console window

Neo4jbat installremove

Neo4j can be installed and run as a Windows Service running without a console window Yoursquollneed to run the scripts with Administrator priveleges Just use the Neo4jbat script with the properargument

bull Neo4jbat install - install as a Windows service

bull will install the service

bull Neo4jbat remove - remove the Neo4j service

bull will stop and remove the Neo4j service

bull Neo4jbat start - will start the Neo4j service

bull will start the Neo4j service if installed or a console

bull session otherwise

bull Neo4jbat stop - stop the Neo4j service if running

Manpages

bull Neo4jbat restart - restart the Neo4j service if installed

bull Neo4jbat status - report on the status of the Neo4j service

bull returns RUNNING STOPPED or NOT INSTALLED

confneo4j-serverpropertiesServer configuration

confneo4j-wrapperconfConfiguration for service wrapper

confneo4jpropertiesTuning configuration for the database

Manpages

Nameneo4j-shell mdash a command-line tool for exploring and manipulating a graph database

Synopsisneo4j-shell [REMOTE OPTIONS]

neo4j-shell [LOCAL OPTIONS]

DESCRIPTIONNeo4j shell is a command-line shell for browsing the graph much like how the Unix shell alongwith commands like cd ls and pwd can be used to browse your local file system The shell canconnect directly to a graph database on the file system To access local a local database used by otherprocesses use the readonly mode

REMOTE OPTIONS

-port PORTPort of host to connect to (default 1337)

-host HOSTDomain name or IP of host to connect to (default localhost)

-name NAMERMI name ie rmilthostgtltportgtltnamegt (default shell)

-readonlyAccess the database in read-only mode The read-only mode enables browsing a database that isused by other processes

LOCAL OPTIONS

-path PATHThe path to the database directory If there is no database at the location a new one will e created

-pid PIDProcess ID to connect to

-c COMMANDCommand line to execute After executing it the shell exits

-config CONFIGThe path to the Neo4j configuration file to be used

EXAMPLESExamples for remote

neo4j-shell

neo4j-shell -port 1337

neo4j-shell -host 1921681234 -port 1337 -name shell

neo4j-shell -host localhost -readonly

Examples for local

neo4j-shell -path pathtodb

Manpages

neo4j-shell -path pathtodb -config pathtoneo4jconfig

neo4j-shell -path pathtodb -readonly

Manpages

Nameneo4j-coordinator mdash Neo4j Coordinator for High-Availability clusters

Synopsisneo4j-coordinator ltcommandgt

DESCRIPTIONNeo4j Coordinator is a server which provides coordination for a Neo4j High Availability Data clusterA coordination cluster must be started and available before the data cluster can be started Thisserver is a member of the cluster

COMMANDS

restartRestarts a running server

condrestartRestarts a server but only if it was already running

dumpDisplays thread dump also saved to the wrapperlog

confcoordcfgCoordination server configuration

confcoord-wrappercfgConfiguration for service wrapper

datacoordinatormyidUnique identifier for coordinator instance

Manpages

Nameneo4j-coordinator-shell mdash Neo4j Coordinator Shell interactive interface

Synopsisneo4j-coordinator-shell -server lthostportgt [ltcmdgt ltargsgt]

DESCRIPTIONNeo4j Coordinator Shell provides an interactive text-based interface to a running Neo4j Coordinatorserver

OPTIONS

-server HOSTPORTConnects to a Neo4j Coordinator at the specified host and port

Table of Contents

Introduction

1 Who should read this

2 Neo4j highlights



11 Deployment Scenarios

111 Server

112 Embedded

12 System Requirements

121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation

131 Embedded Installation

14 Upgrading

141 Normal Upgrade

142 Special Upgrade





15 Usage Data Collector

151 Technical Information

152 How to disable UDC


21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings

221 Configuring heap size and GC

23 File system tuning for high IO

24 Compressed storage of short strings


31 Interaction cycle

32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id

422 Multiple nodes by id

423 Node by index lookup

424 Node by index query

425 Multiple start points

43 Match

431 Related nodes

432 Outgoing relationships

433 Directed relationships and identifier

434 Match by relationship type

435 Match by relationship type and use an identifier

436 Multiple relationships

437 Complex matching

44 Where

441 Boolean operations

442 Filter on node property

443 Regular expressions

444 Filtering on relationship type

445 Property exists

45 Return

451 Return nodes

452 Return relationships

453 Relationship type

454 Return property

455 Identifier with uncommon characters

456 Optional properties

46 Aggregation

461 COUNT

462 Count nodes

463 Count entities

464 Count non null values

465 SUM

466 AVG

467 MAX

468 MIN

47 Order by

471 Order nodes by property

472 Order nodes by multiple properties

473 Order nodes in descending order

474 Ordering null

48 Skip

481 Skip first three

482 Return middle two

49 Limit

491 Return first part


51 Server Installation

511 As a Windows service

512 Linux Service

513 Macintosh Service

514 Multiple Server instances on one machine


521 Important server configurations parameters

522 Neo4j Database performance configuration

523 Logging configuration


Enabling logging from the garbage collector

53 Setup for remote debugging


541 Starting a Neo4j Coordinator

542 Starting the Neo4j Server

55 Using the server with an embedded database

551 Providing custom configuration

56 Server Plugins

57 Tuning the server performance

571 Specifying Neo4j tuning properties

572 Specifying JVM tuning properties


Chapter 6 REST API

61 Service root

611 Get service root

62 Nodes

621 Create node

622 Create node with properties

623 Get node

624 Get non-existent node

625 Delete node

626 Nodes with relationships can not be deleted

63 Relationships

631 Create relationship

632 Get all relationships

633 Get incoming relationships

634 Get outgoing relationships

635 Get typed relationships

636 Get relationships on a node without relationships


641 Get relationship types

65 Node properties

651 Set property on node

652 Update node properties

653 Get properties for node

654 Get properties for node (empty result)

655 Property values can not be null

656 Property values can not be nested

657 Delete all properties from node


661 Update relationship properties

67 Indexes


672 Create node index with configuration

673 Delete node index

674 List node indexes

675 List node indexes (empty result)

676 Add node to index


68 Traversals

681 Traversal using a return filter

682 Creating a paged traverser

683 Paging through the results of a paged traverser

684 Paged traverser page size

685 Paged traverser timeout

69 Built-in Graph Algorithms

691 Find all shortest paths

692 Find one of the shortest paths between nodes

693 Execute a Dijkstra algorithm with similar weights on relationships

694 Execute a Dijkstra algorithm with weights on relationships


6101 Execute multiple operations in batch

6102 Refer to items created earlier in the same batch job

611 Gremlin Plugin

6111 Send a Gremlin Script - URL encoded

6112 Load a sample graph graph

6113 Sort a result using raw Groovy operations

6114 Send a Gremlin Script - JSON encoded with table result

612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query

78 Relationship indexes

79 Scores

710 Configuration and fulltext indexes


7111 Numeric ranges

7112 Sorting

7113 Querying with Lucene Query objects

7114 Compound queries

7115 Default operator

7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search

7133 Runtime Configuration

7134 Updating the Auto Index

7135 Low level details


81 Introduction


91 Architecture

92 Setup and configuration

921 Small

922 Medium

923 Large

924 Installation Notes

93 How Neo4j HA operates


101 Backup

1011 Embedded and Server

1012 High Availability

1013 Restoring Your Data

102 Security

1021 Securing access to the Neo4j Server

103 Monitoring

1031 JMX




Part II Tutorials


111 What is a Graph Database

1111 A Graph contains Nodes and Relationships

1112 Relationships organize the Graph

1113 Query a Graph with a Traversal

1114 Indexes look-up Nodes or Relationships

1115 Neo4j is a Graph Database

112 Comparing Database Models

1121 A Graph Database transforms a RDBMS

1122 A Graph Database elaborates a Key-Value Store

1123 A Graph Database relates Column-Family

1124 A Graph Database navigates a Document Store

113 The Neo4j Graph Database

1131 Relationships

1132 Properties


121 Include Neo4j in your project

1211 Add Neo4j to the build path

1212 Add Neo4j as a dependency

Maven

Ivy

122 Hello world

123 User database with index

124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities

126 Graph Algorithm examples

127 Reading a management attribute

Part III Tools


131 Dashboard tab

1311 Entity chart

1312 Status monitoring

132 Data tab

133 Console tab

134 The Server Info tab


141 Starting the shell

1411 Enabling the shell server

1412 Connecting to a shell server

1413 Pointing the shell to a path

1414 Read-only mode

1415 Run a command and then exit

142 Passing options and arguments

143 Enum options

144 Filters

145 Node titles

146 How to use (individual commands)

1461 Current noderelationship and path

1462 Listing the contents of a noderelationship

1463 Creating nodes and relationships

1464 Setting renaming and removing properties

1465 Deleting nodes and relationships

1466 Environment variables

1467 Executing groovypython scripts

1468 Traverse

1469 Query with Cypher

14610 Indexing

147 Extending the shell Adding your own commands

148 An example shell session




Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator

neo4j-coordinator-shell

The Neo4j Manual v14M06by The Neo4j Team neo4jorg lthttpneo4jorggt neotechnologycom lthttpneotechnologycomgtCopyright copy 2011 Neo Technology

License Creative Commons 30This book is presented in open source and licensed through Creative Commons 30 You are free to copy distribute transmit andor adapt the work Thislicense is based upon the following conditions

Attribution You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or youruse of the work)

Share Alike If you alter transform or build upon this work you may distribute the resulting work only under the same similar or a compatible license

Any of the above conditions can be waived if you get permission from the copyright holder

In no way are any of the following rights affected by the license

bull Your fair dealing or fair use rights

bull The authorrsquos moral rights

bull Rights other persons may have either in the work itself or in how the work is used such as publicity or privacy rights

NoteFor any reuse or distribution you must make clear to the others the license terms of this work The best way to do this is with a direct link tothis page httpcreativecommonsorglicensesby-sa30 lthttpcreativecommonsorglicensesby-sa30gt

Introduction

It features

MinimumIntel 486

Minimum1GB

Recommended4-8GB

MinimumSCSI EIDE

Recommendedext4 ZFS

Java16+

AGPLv3

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

commented out

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Quick info

configured properly

nodestore 9 B Nodes

Configuration

mapped_memory

db mapped_memory

index mapped_memory

mapped_memory

suffixes B k M or G

string_block_size

212 Object cache

Quick info

Configuration

Heap memory usage

Object Size Comment

Relationship

Property

Relationships

Object Size Comment

Number ofprimitives

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

Specifically

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

1 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

1 rows 1 ms

start a=(3)

return abcd

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

1 rows 1 ms

The node

Result

+-----------------------------------------------+

2 rows 1 ms

The node

Result

+---------------------------------+

1 rows 4 ms

Result

+---------------------------------+

1 rows 0 ms

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

Result

+-----------------------------------------------+

1 rows 1 ms

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

Result

+--------+

| nname |

+--------+

1 rows 1 ms

Result

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

1 rows 2 ms

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

Result

+-------------------+

1 rows 1 ms

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Neo4j Server

1 cd $NEO4J_HOME

Neo4j Server

6 binneo4j status

wrappername=neo4j_1

wrappername=neo4j_2

Neo4j Server

Quick info

Neo4j Server

Usage example

srvstart()

srvstop()

srvstart()

Neo4j Server

56 Server Plugins

Quick info

ltdependencygt

Neo4j Server

Override

Source Node source

Expander expander

Neo4j Server

extensions

GetAll

extends graphdb

name get_all_nodes

parameters [ ]

Neo4j Server

Quick info

Neo4j Server

Quick info

Path( helloworld )

Path( nodeId )

Neo4j Server

which results in

Chapter 6 REST API

REST API

61 Service root

Example request

Example response

bull 200 OK

extensions

REST API

62 Nodes

Example response

bull 201 Created

extensions

GraphCloner

foo bar

Example response

bull 201 Created

REST API

foo bar

extensions

GraphCloner

Example request

Example response

bull 200 OK

extensions

REST API

GraphCloner

Example response

bull 404 Not Found

Example response

bull 204 No Content

Example request

Example response

bull 409 Conflict

REST API

Example response

bull 201 Created

type LOVES

extensions

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

type LIKES

extensions

REST API

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

Example request

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

REST API

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

Example response

bull 204 No Content

jim tobias

Example response

bull 204 No Content

Example response

bull 200 OK

foo bar

Example request

REST API

Example response

bull 204 No Content

Example request

foonull

Example response

Example request

foo bar baz

Example response

REST API

bull 204 No Content

REST API

jim tobias

Example response

bull 204 No Content

REST API

Example request

name favorites

Example response

bull 201 Created

Example request

Example response

REST API

bull 201 Created

provider lucene

type fulltext

Example response

bull 204 No Content

Example request

Example response

bull 200 OK

favorites

provider lucene

type exact

Example request

Example response

REST API

bull 204 No Content

Example request

Example response

bull 201 Created

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

extensions

GraphCloner

REST API

bull relationship

bull path

bull fullpath

bull depth_first

bull in

bull out

bull none

bull node_path

REST API

Example request

order breadth_first

return_filter

language javascript

prune_evaluator

name none

language builtin

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

Example request

Example response

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

Example request

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

Example request

REST API

Example response

name 1

extensions

GraphCloner

Example request

Example response

bull 201 Created

REST API

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

bull shortestPath

bull allSimplePaths

bull allPaths

Example request

Example response

bull 200 OK

length 2

Example request

REST API

Example response

bull 200 OK

length 2

Example response

bull 200 OK

weight 20

length 2

Example response

bull 200 OK

weight 60

REST API

length 6

REST API

Example request

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

extensions

GraphCloner

extensions

REST API

GraphCloner

extensions

GraphCloner

fromnode]

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

Example response

bull 200 OK

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

name bob

type KNOWS

extensions

name bob

type KNOWS

extensions

REST API

Example request

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

Example request

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

Example request

Example response

bull 200 OK

REST API

Example request

Example response

bull 200 OK

Chapter 7 Indexing

Indexing

actorsdelete()

Indexing

Actors

Movies

Indexing

bull entity

bull entity key

Indexing

76 Update

index it

Indexing

using exact matches

using a query

txsuccess()

txfinish()

typeHitsclose()

Indexing

int from = 1997

int to = 1999

hits = moviesquery(

Indexing

insertershutdown()

Indexing

txsuccess()

txfailure()

Indexing

finally

txfinish()

assertEquals( node1

assertEquals( node2

assertEquals( rel

indexed

Indexing

txsuccess()

txfailure()

finally

txfinish()

Indexing

txsuccess()

txfailure()

finally

txfinish()

Verify

node2 is updated

assertEquals( node2

assertEquals( node3

bull Shortest paths

bull all paths

bull Dijkstra and

bull A

Graph Algorithms

High Availability

921 Small

922 Medium

923 Large

High Availability

localhost2181

localhost2182

localhost2183

High Availability

Operations

101 Backup

Operations

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

Operations

103 Monitoring

1031 JMX

Operations

Name Description

Operations

String

Integer

String

keys mapped_memory

String

Operations

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

Integer

String

Integer

String

Integer

Operations

Integer

String

boolean

String

Part II Tutorials

records data in

Propert ies

organize

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

Figure 111 RDBMS

B3B5 B7

C1 C2C3

V1D2S2 V2V3V4D1S1

S1D2 S2S3

A Relat ionship

Start node

End node

Relat ionship type

Node loop

follows follows

William

blocks

follows

What How

A Property

Prim it ive

boolean

double

St ring

boolean truefalse

u0000 to uffff (0 to 65535)

Eclipse

NetBeans

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

ltivysettingsgt

ltresolversgt

ltchain name=maingt

ltfilesystemgt

ltchaingt

ltresolversgt

ltivysettingsgt

ltdependenciesgt

EXAMPLE

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

graphDbshutdown()

USERS_REFERENCE

return node

httpwikineo4jorg )

RelTypesUSER )

int idToFind = 45

124 Traversal

DirectionOUTGOING )

depth() + =gt

Override

DirectionOUTGOING )

Get the admins

Get all groups

Override

return false

RoleRelsROOT

The Matrix

breadthFirst()

evaluator(

User roles

Get the admins

breadthFirst()

depthFirst()

Get all groups

breadthFirst()

nodes() )

breadthFirst()

evaluator(

Create a toy graph

Walk the path

new Evaluator()

Override

for ( Path path t )

1244 Social network

Simple social model

bull Person

bull StatusUpdate

depthFirst()

The code looks like

statusesremove( 0 )

firstnext()

sort()

return returnVal

Override

pathweight()

return result

return startTime

Part III Tools

Web Administration

Neo4j Shell

binneo4j-shell

neo4j-shell

neo4j-sh (0)$

Neo4j Shell

relationship

Neo4j Shell

$ set -t int age 29

Neo4j Shell

Override

outprintln( Types )

return null

Neo4j Shell

Current is (0)

set name Jon

send a cypher query

+----------------------+

1 rows 42 ms

where are we

name =[Jon]

ls -avr

Current is (1)

(0)--gt(1)

ls -avr

Appendix A Manpages

Manpages

COMMANDS

Manpages

REMOTE OPTIONS

LOCAL OPTIONS

neo4j-shell

Examples for local

Manpages

COMMANDS

Manpages

OPTIONS

Table of Contents

Introduction


2 Neo4j highlights




111 Server

112 Embedded


121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation


14 Upgrading

141 Normal Upgrade

142 Special Upgrade









21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings






32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id





43 Match

431 Related nodes







44 Where





445 Property exists

45 Return

451 Return nodes



454 Return property



46 Aggregation

461 COUNT

462 Count nodes

463 Count entities


465 SUM

466 AVG

467 MAX

468 MIN

47 Order by




474 Ordering null

48 Skip



49 Limit





512 Linux Service















56 Server Plugins





Chapter 6 REST API

61 Service root


62 Nodes

621 Create node


623 Get node


625 Delete node


63 Relationships









65 Node properties










67 Indexes








68 Traversals














611 Gremlin Plugin





612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query


79 Scores



7111 Numeric ranges

7112 Sorting




7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search





81 Introduction


91 Architecture


921 Small

922 Medium

923 Large




101 Backup




102 Security


103 Monitoring

1031 JMX




Part II Tutorials














1131 Relationships

1132 Properties





Maven

Ivy

122 Hello world


124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities



Part III Tools


131 Dashboard tab

1311 Entity chart


132 Data tab

133 Console tab







1414 Read-only mode



143 Enum options

144 Filters

145 Node titles









1468 Traverse


14610 Indexing






Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator


Introduction

It features

MinimumIntel 486

Minimum1GB

Recommended4-8GB

MinimumSCSI EIDE

Recommendedext4 ZFS

Java16+

AGPLv3

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

commented out

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Quick info

configured properly

nodestore 9 B Nodes

Configuration

mapped_memory

db mapped_memory

index mapped_memory

mapped_memory

suffixes B k M or G

string_block_size

212 Object cache

Quick info

Configuration

Heap memory usage

Object Size Comment

Relationship

Property

Relationships

Object Size Comment

Number ofprimitives

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

Specifically

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

1 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

1 rows 1 ms

start a=(3)

return abcd

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

1 rows 1 ms

The node

Result

+-----------------------------------------------+

2 rows 1 ms

The node

Result

+---------------------------------+

1 rows 4 ms

Result

+---------------------------------+

1 rows 0 ms

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

Result

+-----------------------------------------------+

1 rows 1 ms

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

Result

+--------+

| nname |

+--------+

1 rows 1 ms

Result

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

1 rows 2 ms

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

Result

+-------------------+

1 rows 1 ms

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Neo4j Server

1 cd $NEO4J_HOME

Neo4j Server

6 binneo4j status

wrappername=neo4j_1

wrappername=neo4j_2

Neo4j Server

Quick info

Neo4j Server

Usage example

srvstart()

srvstop()

srvstart()

Neo4j Server

56 Server Plugins

Quick info

ltdependencygt

Neo4j Server

Override

Source Node source

Expander expander

Neo4j Server

extensions

GetAll

extends graphdb

name get_all_nodes

parameters [ ]

Neo4j Server

Quick info

Neo4j Server

Quick info

Path( helloworld )

Path( nodeId )

Neo4j Server

which results in

Chapter 6 REST API

REST API

61 Service root

Example request

Example response

bull 200 OK

extensions

REST API

62 Nodes

Example response

bull 201 Created

extensions

GraphCloner

foo bar

Example response

bull 201 Created

REST API

foo bar

extensions

GraphCloner

Example request

Example response

bull 200 OK

extensions

REST API

GraphCloner

Example response

bull 404 Not Found

Example response

bull 204 No Content

Example request

Example response

bull 409 Conflict

REST API

Example response

bull 201 Created

type LOVES

extensions

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

type LIKES

extensions

REST API

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

Example request

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

REST API

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

Example response

bull 204 No Content

jim tobias

Example response

bull 204 No Content

Example response

bull 200 OK

foo bar

Example request

REST API

Example response

bull 204 No Content

Example request

foonull

Example response

Example request

foo bar baz

Example response

REST API

bull 204 No Content

REST API

jim tobias

Example response

bull 204 No Content

REST API

Example request

name favorites

Example response

bull 201 Created

Example request

Example response

REST API

bull 201 Created

provider lucene

type fulltext

Example response

bull 204 No Content

Example request

Example response

bull 200 OK

favorites

provider lucene

type exact

Example request

Example response

REST API

bull 204 No Content

Example request

Example response

bull 201 Created

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

extensions

GraphCloner

REST API

bull relationship

bull path

bull fullpath

bull depth_first

bull in

bull out

bull none

bull node_path

REST API

Example request

order breadth_first

return_filter

language javascript

prune_evaluator

name none

language builtin

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

Example request

Example response

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

Example request

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

Example request

REST API

Example response

name 1

extensions

GraphCloner

Example request

Example response

bull 201 Created

REST API

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

bull shortestPath

bull allSimplePaths

bull allPaths

Example request

Example response

bull 200 OK

length 2

Example request

REST API

Example response

bull 200 OK

length 2

Example response

bull 200 OK

weight 20

length 2

Example response

bull 200 OK

weight 60

REST API

length 6

REST API

Example request

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

extensions

GraphCloner

extensions

REST API

GraphCloner

extensions

GraphCloner

fromnode]

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

Example response

bull 200 OK

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

name bob

type KNOWS

extensions

name bob

type KNOWS

extensions

REST API

Example request

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

Example request

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

Example request

Example response

bull 200 OK

REST API

Example request

Example response

bull 200 OK

Chapter 7 Indexing

Indexing

actorsdelete()

Indexing

Actors

Movies

Indexing

bull entity

bull entity key

Indexing

76 Update

index it

Indexing

using exact matches

using a query

txsuccess()

txfinish()

typeHitsclose()

Indexing

int from = 1997

int to = 1999

hits = moviesquery(

Indexing

insertershutdown()

Indexing

txsuccess()

txfailure()

Indexing

finally

txfinish()

assertEquals( node1

assertEquals( node2

assertEquals( rel

indexed

Indexing

txsuccess()

txfailure()

finally

txfinish()

Indexing

txsuccess()

txfailure()

finally

txfinish()

Verify

node2 is updated

assertEquals( node2

assertEquals( node3

bull Shortest paths

bull all paths

bull Dijkstra and

bull A

Graph Algorithms

High Availability

921 Small

922 Medium

923 Large

High Availability

localhost2181

localhost2182

localhost2183

High Availability

Operations

101 Backup

Operations

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

Operations

103 Monitoring

1031 JMX

Operations

Name Description

Operations

String

Integer

String

keys mapped_memory

String

Operations

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

Integer

String

Integer

String

Integer

Operations

Integer

String

boolean

String

Part II Tutorials

records data in

Propert ies

organize

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

Figure 111 RDBMS

B3B5 B7

C1 C2C3

V1D2S2 V2V3V4D1S1

S1D2 S2S3

A Relat ionship

Start node

End node

Relat ionship type

Node loop

follows follows

William

blocks

follows

What How

A Property

Prim it ive

boolean

double

St ring

boolean truefalse

u0000 to uffff (0 to 65535)

Eclipse

NetBeans

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

ltivysettingsgt

ltresolversgt

ltchain name=maingt

ltfilesystemgt

ltchaingt

ltresolversgt

ltivysettingsgt

ltdependenciesgt

EXAMPLE

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

graphDbshutdown()

USERS_REFERENCE

return node

httpwikineo4jorg )

RelTypesUSER )

int idToFind = 45

124 Traversal

DirectionOUTGOING )

depth() + =gt

Override

DirectionOUTGOING )

Get the admins

Get all groups

Override

return false

RoleRelsROOT

The Matrix

breadthFirst()

evaluator(

User roles

Get the admins

breadthFirst()

depthFirst()

Get all groups

breadthFirst()

nodes() )

breadthFirst()

evaluator(

Create a toy graph

Walk the path

new Evaluator()

Override

for ( Path path t )

1244 Social network

Simple social model

bull Person

bull StatusUpdate

depthFirst()

The code looks like

statusesremove( 0 )

firstnext()

sort()

return returnVal

Override

pathweight()

return result

return startTime

Part III Tools

Web Administration

Neo4j Shell

binneo4j-shell

neo4j-shell

neo4j-sh (0)$

Neo4j Shell

relationship

Neo4j Shell

$ set -t int age 29

Neo4j Shell

Override

outprintln( Types )

return null

Neo4j Shell

Current is (0)

set name Jon

send a cypher query

+----------------------+

1 rows 42 ms

where are we

name =[Jon]

ls -avr

Current is (1)

(0)--gt(1)

ls -avr

Appendix A Manpages

Manpages

COMMANDS

Manpages

REMOTE OPTIONS

LOCAL OPTIONS

neo4j-shell

Examples for local

Manpages

COMMANDS

Manpages

OPTIONS

Table of Contents

Introduction


2 Neo4j highlights




111 Server

112 Embedded


121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation


14 Upgrading

141 Normal Upgrade

142 Special Upgrade









21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings






32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id





43 Match

431 Related nodes







44 Where





445 Property exists

45 Return

451 Return nodes



454 Return property



46 Aggregation

461 COUNT

462 Count nodes

463 Count entities


465 SUM

466 AVG

467 MAX

468 MIN

47 Order by




474 Ordering null

48 Skip



49 Limit





512 Linux Service















56 Server Plugins





Chapter 6 REST API

61 Service root


62 Nodes

621 Create node


623 Get node


625 Delete node


63 Relationships









65 Node properties










67 Indexes








68 Traversals














611 Gremlin Plugin





612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query


79 Scores



7111 Numeric ranges

7112 Sorting




7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search





81 Introduction


91 Architecture


921 Small

922 Medium

923 Large




101 Backup




102 Security


103 Monitoring

1031 JMX




Part II Tutorials














1131 Relationships

1132 Properties





Maven

Ivy

122 Hello world


124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities



Part III Tools


131 Dashboard tab

1311 Entity chart


132 Data tab

133 Console tab







1414 Read-only mode



143 Enum options

144 Filters

145 Node titles









1468 Traverse


14610 Indexing






Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator


Introduction

It features

MinimumIntel 486

Minimum1GB

Recommended4-8GB

MinimumSCSI EIDE

Recommendedext4 ZFS

Java16+

AGPLv3

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

commented out

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Quick info

configured properly

nodestore 9 B Nodes

Configuration

mapped_memory

db mapped_memory

index mapped_memory

mapped_memory

suffixes B k M or G

string_block_size

212 Object cache

Quick info

Configuration

Heap memory usage

Object Size Comment

Relationship

Property

Relationships

Object Size Comment

Number ofprimitives

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

Specifically

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

1 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

1 rows 1 ms

start a=(3)

return abcd

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

1 rows 1 ms

The node

Result

+-----------------------------------------------+

2 rows 1 ms

The node

Result

+---------------------------------+

1 rows 4 ms

Result

+---------------------------------+

1 rows 0 ms

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

Result

+-----------------------------------------------+

1 rows 1 ms

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

Result

+--------+

| nname |

+--------+

1 rows 1 ms

Result

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

1 rows 2 ms

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

Result

+-------------------+

1 rows 1 ms

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Neo4j Server

1 cd $NEO4J_HOME

Neo4j Server

6 binneo4j status

wrappername=neo4j_1

wrappername=neo4j_2

Neo4j Server

Quick info

Neo4j Server

Usage example

srvstart()

srvstop()

srvstart()

Neo4j Server

56 Server Plugins

Quick info

ltdependencygt

Neo4j Server

Override

Source Node source

Expander expander

Neo4j Server

extensions

GetAll

extends graphdb

name get_all_nodes

parameters [ ]

Neo4j Server

Quick info

Neo4j Server

Quick info

Path( helloworld )

Path( nodeId )

Neo4j Server

which results in

Chapter 6 REST API

REST API

61 Service root

Example request

Example response

bull 200 OK

extensions

REST API

62 Nodes

Example response

bull 201 Created

extensions

GraphCloner

foo bar

Example response

bull 201 Created

REST API

foo bar

extensions

GraphCloner

Example request

Example response

bull 200 OK

extensions

REST API

GraphCloner

Example response

bull 404 Not Found

Example response

bull 204 No Content

Example request

Example response

bull 409 Conflict

REST API

Example response

bull 201 Created

type LOVES

extensions

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

type LIKES

extensions

REST API

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

Example request

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

REST API

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

Example response

bull 204 No Content

jim tobias

Example response

bull 204 No Content

Example response

bull 200 OK

foo bar

Example request

REST API

Example response

bull 204 No Content

Example request

foonull

Example response

Example request

foo bar baz

Example response

REST API

bull 204 No Content

REST API

jim tobias

Example response

bull 204 No Content

REST API

Example request

name favorites

Example response

bull 201 Created

Example request

Example response

REST API

bull 201 Created

provider lucene

type fulltext

Example response

bull 204 No Content

Example request

Example response

bull 200 OK

favorites

provider lucene

type exact

Example request

Example response

REST API

bull 204 No Content

Example request

Example response

bull 201 Created

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

extensions

GraphCloner

REST API

bull relationship

bull path

bull fullpath

bull depth_first

bull in

bull out

bull none

bull node_path

REST API

Example request

order breadth_first

return_filter

language javascript

prune_evaluator

name none

language builtin

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

Example request

Example response

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

Example request

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

Example request

REST API

Example response

name 1

extensions

GraphCloner

Example request

Example response

bull 201 Created

REST API

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

bull shortestPath

bull allSimplePaths

bull allPaths

Example request

Example response

bull 200 OK

length 2

Example request

REST API

Example response

bull 200 OK

length 2

Example response

bull 200 OK

weight 20

length 2

Example response

bull 200 OK

weight 60

REST API

length 6

REST API

Example request

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

extensions

GraphCloner

extensions

REST API

GraphCloner

extensions

GraphCloner

fromnode]

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

Example response

bull 200 OK

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

name bob

type KNOWS

extensions

name bob

type KNOWS

extensions

REST API

Example request

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

Example request

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

Example request

Example response

bull 200 OK

REST API

Example request

Example response

bull 200 OK

Chapter 7 Indexing

Indexing

actorsdelete()

Indexing

Actors

Movies

Indexing

bull entity

bull entity key

Indexing

76 Update

index it

Indexing

using exact matches

using a query

txsuccess()

txfinish()

typeHitsclose()

Indexing

int from = 1997

int to = 1999

hits = moviesquery(

Indexing

insertershutdown()

Indexing

txsuccess()

txfailure()

Indexing

finally

txfinish()

assertEquals( node1

assertEquals( node2

assertEquals( rel

indexed

Indexing

txsuccess()

txfailure()

finally

txfinish()

Indexing

txsuccess()

txfailure()

finally

txfinish()

Verify

node2 is updated

assertEquals( node2

assertEquals( node3

bull Shortest paths

bull all paths

bull Dijkstra and

bull A

Graph Algorithms

High Availability

921 Small

922 Medium

923 Large

High Availability

localhost2181

localhost2182

localhost2183

High Availability

Operations

101 Backup

Operations

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

Operations

103 Monitoring

1031 JMX

Operations

Name Description

Operations

String

Integer

String

keys mapped_memory

String

Operations

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

Integer

String

Integer

String

Integer

Operations

Integer

String

boolean

String

Part II Tutorials

records data in

Propert ies

organize

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

Figure 111 RDBMS

B3B5 B7

C1 C2C3

V1D2S2 V2V3V4D1S1

S1D2 S2S3

A Relat ionship

Start node

End node

Relat ionship type

Node loop

follows follows

William

blocks

follows

What How

A Property

Prim it ive

boolean

double

St ring

boolean truefalse

u0000 to uffff (0 to 65535)

Eclipse

NetBeans

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

ltivysettingsgt

ltresolversgt

ltchain name=maingt

ltfilesystemgt

ltchaingt

ltresolversgt

ltivysettingsgt

ltdependenciesgt

EXAMPLE

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

graphDbshutdown()

USERS_REFERENCE

return node

httpwikineo4jorg )

RelTypesUSER )

int idToFind = 45

124 Traversal

DirectionOUTGOING )

depth() + =gt

Override

DirectionOUTGOING )

Get the admins

Get all groups

Override

return false

RoleRelsROOT

The Matrix

breadthFirst()

evaluator(

User roles

Get the admins

breadthFirst()

depthFirst()

Get all groups

breadthFirst()

nodes() )

breadthFirst()

evaluator(

Create a toy graph

Walk the path

new Evaluator()

Override

for ( Path path t )

1244 Social network

Simple social model

bull Person

bull StatusUpdate

depthFirst()

The code looks like

statusesremove( 0 )

firstnext()

sort()

return returnVal

Override

pathweight()

return result

return startTime

Part III Tools

Web Administration

Neo4j Shell

binneo4j-shell

neo4j-shell

neo4j-sh (0)$

Neo4j Shell

relationship

Neo4j Shell

$ set -t int age 29

Neo4j Shell

Override

outprintln( Types )

return null

Neo4j Shell

Current is (0)

set name Jon

send a cypher query

+----------------------+

1 rows 42 ms

where are we

name =[Jon]

ls -avr

Current is (1)

(0)--gt(1)

ls -avr

Appendix A Manpages

Manpages

COMMANDS

Manpages

REMOTE OPTIONS

LOCAL OPTIONS

neo4j-shell

Examples for local

Manpages

COMMANDS

Manpages

OPTIONS

Table of Contents

Introduction


2 Neo4j highlights




111 Server

112 Embedded


121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation


14 Upgrading

141 Normal Upgrade

142 Special Upgrade









21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings






32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id





43 Match

431 Related nodes







44 Where





445 Property exists

45 Return

451 Return nodes



454 Return property



46 Aggregation

461 COUNT

462 Count nodes

463 Count entities


465 SUM

466 AVG

467 MAX

468 MIN

47 Order by




474 Ordering null

48 Skip



49 Limit





512 Linux Service















56 Server Plugins





Chapter 6 REST API

61 Service root


62 Nodes

621 Create node


623 Get node


625 Delete node


63 Relationships









65 Node properties










67 Indexes








68 Traversals














611 Gremlin Plugin





612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query


79 Scores



7111 Numeric ranges

7112 Sorting




7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search





81 Introduction


91 Architecture


921 Small

922 Medium

923 Large




101 Backup




102 Security


103 Monitoring

1031 JMX




Part II Tutorials














1131 Relationships

1132 Properties





Maven

Ivy

122 Hello world


124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities



Part III Tools


131 Dashboard tab

1311 Entity chart


132 Data tab

133 Console tab







1414 Read-only mode



143 Enum options

144 Filters

145 Node titles









1468 Traverse


14610 Indexing






Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator


Introduction

It features

MinimumIntel 486

Minimum1GB

Recommended4-8GB

MinimumSCSI EIDE

Recommendedext4 ZFS

Java16+

AGPLv3

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

commented out

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Quick info

configured properly

nodestore 9 B Nodes

Configuration

mapped_memory

db mapped_memory

index mapped_memory

mapped_memory

suffixes B k M or G

string_block_size

212 Object cache

Quick info

Configuration

Heap memory usage

Object Size Comment

Relationship

Property

Relationships

Object Size Comment

Number ofprimitives

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

Specifically

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

1 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

1 rows 1 ms

start a=(3)

return abcd

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

1 rows 1 ms

The node

Result

+-----------------------------------------------+

2 rows 1 ms

The node

Result

+---------------------------------+

1 rows 4 ms

Result

+---------------------------------+

1 rows 0 ms

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

Result

+-----------------------------------------------+

1 rows 1 ms

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

Result

+--------+

| nname |

+--------+

1 rows 1 ms

Result

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

1 rows 2 ms

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

Result

+-------------------+

1 rows 1 ms

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Neo4j Server

1 cd $NEO4J_HOME

Neo4j Server

6 binneo4j status

wrappername=neo4j_1

wrappername=neo4j_2

Neo4j Server

Quick info

Neo4j Server

Usage example

srvstart()

srvstop()

srvstart()

Neo4j Server

56 Server Plugins

Quick info

ltdependencygt

Neo4j Server

Override

Source Node source

Expander expander

Neo4j Server

extensions

GetAll

extends graphdb

name get_all_nodes

parameters [ ]

Neo4j Server

Quick info

Neo4j Server

Quick info

Path( helloworld )

Path( nodeId )

Neo4j Server

which results in

Chapter 6 REST API

REST API

61 Service root

Example request

Example response

bull 200 OK

extensions

REST API

62 Nodes

Example response

bull 201 Created

extensions

GraphCloner

foo bar

Example response

bull 201 Created

REST API

foo bar

extensions

GraphCloner

Example request

Example response

bull 200 OK

extensions

REST API

GraphCloner

Example response

bull 404 Not Found

Example response

bull 204 No Content

Example request

Example response

bull 409 Conflict

REST API

Example response

bull 201 Created

type LOVES

extensions

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

type LIKES

extensions

REST API

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

Example request

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

REST API

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

Example response

bull 204 No Content

jim tobias

Example response

bull 204 No Content

Example response

bull 200 OK

foo bar

Example request

REST API

Example response

bull 204 No Content

Example request

foonull

Example response

Example request

foo bar baz

Example response

REST API

bull 204 No Content

REST API

jim tobias

Example response

bull 204 No Content

REST API

Example request

name favorites

Example response

bull 201 Created

Example request

Example response

REST API

bull 201 Created

provider lucene

type fulltext

Example response

bull 204 No Content

Example request

Example response

bull 200 OK

favorites

provider lucene

type exact

Example request

Example response

REST API

bull 204 No Content

Example request

Example response

bull 201 Created

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

extensions

GraphCloner

REST API

bull relationship

bull path

bull fullpath

bull depth_first

bull in

bull out

bull none

bull node_path

REST API

Example request

order breadth_first

return_filter

language javascript

prune_evaluator

name none

language builtin

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

Example request

Example response

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

Example request

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

Example request

REST API

Example response

name 1

extensions

GraphCloner

Example request

Example response

bull 201 Created

REST API

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

bull shortestPath

bull allSimplePaths

bull allPaths

Example request

Example response

bull 200 OK

length 2

Example request

REST API

Example response

bull 200 OK

length 2

Example response

bull 200 OK

weight 20

length 2

Example response

bull 200 OK

weight 60

REST API

length 6

REST API

Example request

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

extensions

GraphCloner

extensions

REST API

GraphCloner

extensions

GraphCloner

fromnode]

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

Example response

bull 200 OK

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

name bob

type KNOWS

extensions

name bob

type KNOWS

extensions

REST API

Example request

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

Example request

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

Example request

Example response

bull 200 OK

REST API

Example request

Example response

bull 200 OK

Chapter 7 Indexing

Indexing

actorsdelete()

Indexing

Actors

Movies

Indexing

bull entity

bull entity key

Indexing

76 Update

index it

Indexing

using exact matches

using a query

txsuccess()

txfinish()

typeHitsclose()

Indexing

int from = 1997

int to = 1999

hits = moviesquery(

Indexing

insertershutdown()

Indexing

txsuccess()

txfailure()

Indexing

finally

txfinish()

assertEquals( node1

assertEquals( node2

assertEquals( rel

indexed

Indexing

txsuccess()

txfailure()

finally

txfinish()

Indexing

txsuccess()

txfailure()

finally

txfinish()

Verify

node2 is updated

assertEquals( node2

assertEquals( node3

bull Shortest paths

bull all paths

bull Dijkstra and

bull A

Graph Algorithms

High Availability

921 Small

922 Medium

923 Large

High Availability

localhost2181

localhost2182

localhost2183

High Availability

Operations

101 Backup

Operations

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

Operations

103 Monitoring

1031 JMX

Operations

Name Description

Operations

String

Integer

String

keys mapped_memory

String

Operations

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

Integer

String

Integer

String

Integer

Operations

Integer

String

boolean

String

Part II Tutorials

records data in

Propert ies

organize

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

Figure 111 RDBMS

B3B5 B7

C1 C2C3

V1D2S2 V2V3V4D1S1

S1D2 S2S3

A Relat ionship

Start node

End node

Relat ionship type

Node loop

follows follows

William

blocks

follows

What How

A Property

Prim it ive

boolean

double

St ring

boolean truefalse

u0000 to uffff (0 to 65535)

Eclipse

NetBeans

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

ltivysettingsgt

ltresolversgt

ltchain name=maingt

ltfilesystemgt

ltchaingt

ltresolversgt

ltivysettingsgt

ltdependenciesgt

EXAMPLE

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

graphDbshutdown()

USERS_REFERENCE

return node

httpwikineo4jorg )

RelTypesUSER )

int idToFind = 45

124 Traversal

DirectionOUTGOING )

depth() + =gt

Override

DirectionOUTGOING )

Get the admins

Get all groups

Override

return false

RoleRelsROOT

The Matrix

breadthFirst()

evaluator(

User roles

Get the admins

breadthFirst()

depthFirst()

Get all groups

breadthFirst()

nodes() )

breadthFirst()

evaluator(

Create a toy graph

Walk the path

new Evaluator()

Override

for ( Path path t )

1244 Social network

Simple social model

bull Person

bull StatusUpdate

depthFirst()

The code looks like

statusesremove( 0 )

firstnext()

sort()

return returnVal

Override

pathweight()

return result

return startTime

Part III Tools

Web Administration

Neo4j Shell

binneo4j-shell

neo4j-shell

neo4j-sh (0)$

Neo4j Shell

relationship

Neo4j Shell

$ set -t int age 29

Neo4j Shell

Override

outprintln( Types )

return null

Neo4j Shell

Current is (0)

set name Jon

send a cypher query

+----------------------+

1 rows 42 ms

where are we

name =[Jon]

ls -avr

Current is (1)

(0)--gt(1)

ls -avr

Appendix A Manpages

Manpages

COMMANDS

Manpages

REMOTE OPTIONS

LOCAL OPTIONS

neo4j-shell

Examples for local

Manpages

COMMANDS

Manpages

OPTIONS

Table of Contents

Introduction


2 Neo4j highlights




111 Server

112 Embedded


121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation


14 Upgrading

141 Normal Upgrade

142 Special Upgrade









21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings






32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id





43 Match

431 Related nodes







44 Where





445 Property exists

45 Return

451 Return nodes



454 Return property



46 Aggregation

461 COUNT

462 Count nodes

463 Count entities


465 SUM

466 AVG

467 MAX

468 MIN

47 Order by




474 Ordering null

48 Skip



49 Limit





512 Linux Service















56 Server Plugins





Chapter 6 REST API

61 Service root


62 Nodes

621 Create node


623 Get node


625 Delete node


63 Relationships









65 Node properties










67 Indexes








68 Traversals














611 Gremlin Plugin





612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query


79 Scores



7111 Numeric ranges

7112 Sorting




7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search





81 Introduction


91 Architecture


921 Small

922 Medium

923 Large




101 Backup




102 Security


103 Monitoring

1031 JMX




Part II Tutorials














1131 Relationships

1132 Properties





Maven

Ivy

122 Hello world


124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities



Part III Tools


131 Dashboard tab

1311 Entity chart


132 Data tab

133 Console tab







1414 Read-only mode



143 Enum options

144 Filters

145 Node titles









1468 Traverse


14610 Indexing






Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator


Introduction

It features

MinimumIntel 486

Minimum1GB

Recommended4-8GB

MinimumSCSI EIDE

Recommendedext4 ZFS

Java16+

AGPLv3

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

commented out

ltdependencygt

ltexclusionsgt

ltexclusiongt

ltexclusionsgt

ltdependencygt

Quick info

configured properly

nodestore 9 B Nodes

Configuration

mapped_memory

db mapped_memory

index mapped_memory

mapped_memory

suffixes B k M or G

string_block_size

212 Object cache

Quick info

Configuration

Heap memory usage

Object Size Comment

Relationship

Property

Relationships

Object Size Comment

Number ofprimitives

100M 8GB+ 1-4GB 1-2GB

1B+ 16GB-32GB+ 4GB+ 1-2GB

Specifically

Result

+-----------+

| Node[0] |

+-----------+

1 rows 0 ms

Result

+--------------------+

| Node[1]name-gtA |

| Node[2]name-gtB |

| Node[3]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 1 ms

Result

+--------------------+

| Node[1]name-gtA |

+--------------------+

1 rows 0 ms

Result

+-----------------------------------------+

| a | b |

+-----------------------------------------+

1 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[1]name-gtD |

| Node[5]name-gtC |

+--------------------+

3 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 2 ms

Result

+---------------+

| KNOWS[0] |

| BLOCKS[1] |

+---------------+

2 rows 1 ms

Result

+--------------------+

| Node[5]name-gtC |

+--------------------+

1 rows 1 ms

Result

+---------------+

| BLOCKS[1] |

+---------------+

1 rows 1 ms

Result

+--------------------------------------------------------------+

| a | b | c |

+--------------------------------------------------------------+

1 rows 1 ms

start a=(3)

return abcd

Result

+-----------------------------------------------------------------------------------+

| a | b | c | d |

+-----------------------------------------------------------------------------------+

1 rows 1 ms

The node

Result

+-----------------------------------------------+

2 rows 1 ms

The node

Result

+---------------------------------+

1 rows 4 ms

Result

+---------------------------------+

1 rows 0 ms

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 1 ms

Result

+-----------------------------------------------+

1 rows 1 ms

The node

Result

+--------------------+

| Node[2]name-gtB |

+--------------------+

1 rows 0 ms

The relationship

Result

+--------------+

| KNOWS[0] |

+--------------+

1 rows 0 ms

Result

+--------+

| r~TYPE |

+--------+

| KNOWS |

| BLOCKS |

+--------+

2 rows 1 ms

Result

+--------+

| nname |

+--------+

1 rows 1 ms

Result

+-------------------------------------------+

| Yes |

+-------------------------------------------+

1 rows 0 ms

Result

+--------+

| nage |

+--------+

| 55 |

| ltnullgt |

+--------+

2 rows 1 ms

Result

+--------------------------------------------+

| n | count() |

+--------------------------------------------+

1 rows 2 ms

Result

+----------+

| count(x) |

+----------+

1 rows 1 ms

Result

+-------------------+

1 rows 1 ms

Result

+-----------------+

| sum(nproperty) |

+-----------------+

| 90 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| avg(nproperty) |

+-----------------+

| 300 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| max(nproperty) |

+-----------------+

| 44 |

+-----------------+

1 rows 1 ms

Result

+-----------------+

| min(nproperty) |

+-----------------+

| 13 |

+-----------------+

1 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+----------------------------------------+

3 rows 1 ms

Result

+---------------------------------------------------+

| nlength | n |

+---------------------------------------------------+

3 rows 1 ms

Result

+--------------------+

| Node[1]name-gtD |

| Node[2]name-gtE |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

2 rows 1 ms

Result

+--------------------+

| Node[3]name-gtA |

| Node[4]name-gtB |

| Node[5]name-gtC |

+--------------------+

3 rows 3 ms

Neo4j Server

1 cd $NEO4J_HOME

Neo4j Server

6 binneo4j status

wrappername=neo4j_1

wrappername=neo4j_2

Neo4j Server

Quick info

Neo4j Server

Usage example

srvstart()

srvstop()

srvstart()

Neo4j Server

56 Server Plugins

Quick info

ltdependencygt

Neo4j Server

Override

Source Node source

Expander expander

Neo4j Server

extensions

GetAll

extends graphdb

name get_all_nodes

parameters [ ]

Neo4j Server

Quick info

Neo4j Server

Quick info

Path( helloworld )

Path( nodeId )

Neo4j Server

which results in

Chapter 6 REST API

REST API

61 Service root

Example request

Example response

bull 200 OK

extensions

REST API

62 Nodes

Example response

bull 201 Created

extensions

GraphCloner

foo bar

Example response

bull 201 Created

REST API

foo bar

extensions

GraphCloner

Example request

Example response

bull 200 OK

extensions

REST API

GraphCloner

Example response

bull 404 Not Found

Example response

bull 204 No Content

Example request

Example response

bull 409 Conflict

REST API

Example response

bull 201 Created

type LOVES

extensions

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

type LIKES

extensions

REST API

Example response

bull 200 OK

type LIKES

extensions

type HATES

extensions

Example request

Example response

bull 200 OK

REST API

type LIKES

extensions

type LIKES

extensions

type HATES

extensions

Example response

bull 200 OK

REST API

Example response

bull 200 OK

[foobar]

REST API

65 Node properties

Example response

bull 204 No Content

jim tobias

Example response

bull 204 No Content

Example response

bull 200 OK

foo bar

Example request

REST API

Example response

bull 204 No Content

Example request

foonull

Example response

Example request

foo bar baz

Example response

REST API

bull 204 No Content

REST API

jim tobias

Example response

bull 204 No Content

REST API

Example request

name favorites

Example response

bull 201 Created

Example request

Example response

REST API

bull 201 Created

provider lucene

type fulltext

Example response

bull 204 No Content

Example request

Example response

bull 200 OK

favorites

provider lucene

type exact

Example request

Example response

REST API

bull 204 No Content

Example request

Example response

bull 201 Created

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

extensions

GraphCloner

REST API

bull relationship

bull path

bull fullpath

bull depth_first

bull in

bull out

bull none

bull node_path

REST API

Example request

order breadth_first

return_filter

language javascript

prune_evaluator

name none

language builtin

max depth 3

relationships [

direction all

type knows

direction all

type loves

Example response

name Root

extensions

GraphCloner

REST API

name Mattias

extensions

GraphCloner

name Peter

extensions

GraphCloner

name Tobias

REST API

extensions

GraphCloner

Example request

Example response

name 1

extensions

REST API

GraphCloner

name 10

extensions

GraphCloner

name 11

extensions

GraphCloner

REST API

name 12

extensions

GraphCloner

name 13

extensions

GraphCloner

name 14

REST API

extensions

GraphCloner

name 15

extensions

GraphCloner

name 16

extensions

REST API

GraphCloner

name 17

extensions

GraphCloner

name 18

extensions

GraphCloner

REST API

name 19

extensions

GraphCloner

name 21

extensions

GraphCloner

name 31

REST API

extensions

GraphCloner

Example request

Example response

name 331

REST API

extensions

GraphCloner

name 341

extensions

GraphCloner

name 351

extensions

REST API

GraphCloner

name 361

extensions

GraphCloner

name 371

extensions

GraphCloner

REST API

name 381

extensions

GraphCloner

name 391

extensions

GraphCloner

name 401

REST API

extensions

GraphCloner

name 410

extensions

GraphCloner

name 411

extensions

REST API

GraphCloner

name 412

extensions

GraphCloner

name 413

extensions

GraphCloner

REST API

name 414

extensions

GraphCloner

name 415

extensions

GraphCloner

name 416

REST API

extensions

GraphCloner

name 417

extensions

GraphCloner

name 418

extensions

REST API

GraphCloner

name 419

extensions

GraphCloner

name 421

extensions

GraphCloner

REST API

name 431

extensions

GraphCloner

name 441

extensions

GraphCloner

Example request

REST API

Example response

name 1

extensions

GraphCloner

Example request

Example response

bull 201 Created

REST API

name 1

extensions

GraphCloner

name 10

extensions

GraphCloner

name 11

REST API

extensions

GraphCloner

name 12

extensions

GraphCloner

name 13

extensions

REST API

GraphCloner

name 14

extensions

GraphCloner

name 15

extensions

GraphCloner

REST API

name 16

extensions

GraphCloner

name 17

extensions

GraphCloner

REST API

name 18

extensions

GraphCloner

name 19

extensions

GraphCloner

name 21

REST API

extensions

GraphCloner

name 31

extensions

GraphCloner

REST API

bull shortestPath

bull allSimplePaths

bull allPaths

Example request

Example response

bull 200 OK

length 2

Example request

REST API

Example response

bull 200 OK

length 2

Example response

bull 200 OK

weight 20

length 2

Example response

bull 200 OK

weight 60

REST API

length 6

REST API

Example request

methodPUT

tonode0properties

methodGET

tonode0

REST API

methodPOST

tonode

methodPOST

tonode

Example response

bull 200 OK

extensions

GraphCloner

extensions

REST API

GraphCloner

extensions

GraphCloner

fromnode]

Example request

methodPOST

tonode

REST API

methodPOST

tonode

methodPOST

to0relationships

namebob

typeKNOWS

methodPOST

Example response

bull 200 OK

extensions

GraphCloner

REST API

age 12

extensions

GraphCloner

name bob

type KNOWS

extensions

name bob

type KNOWS

extensions

REST API

Example request

Example response

bull 200 OK

name you

extensions

GraphCloner

REST API

Example request

Example response

extensions

GraphCloner

name I

extensions

REST API

GraphCloner

name you

extensions

GraphCloner

name him

extensions

GraphCloner

REST API

Example request

Example response

bull 200 OK

name him

extensions

GraphCloner

name you

REST API

extensions

GraphCloner

Example request

Example response

bull 200 OK

REST API

Example request

Example response

bull 200 OK

Chapter 7 Indexing

Indexing

actorsdelete()

Indexing

Actors

Movies

Indexing

bull entity

bull entity key

Indexing

76 Update

index it

Indexing

using exact matches

using a query

txsuccess()

txfinish()

typeHitsclose()

Indexing

int from = 1997

int to = 1999

hits = moviesquery(

Indexing

insertershutdown()

Indexing

txsuccess()

txfailure()

Indexing

finally

txfinish()

assertEquals( node1

assertEquals( node2

assertEquals( rel

indexed

Indexing

txsuccess()

txfailure()

finally

txfinish()

Indexing

txsuccess()

txfailure()

finally

txfinish()

Verify

node2 is updated

assertEquals( node2

assertEquals( node3

bull Shortest paths

bull all paths

bull Dijkstra and

bull A

Graph Algorithms

High Availability

921 Small

922 Medium

923 Large

High Availability

localhost2181

localhost2182

localhost2183

High Availability

Operations

101 Backup

Operations

ltProxy gt

Order DenyAllow

Deny from all

Allow from 1921680

ltProxygt

Operations

103 Monitoring

1031 JMX

Operations

Name Description

Operations

String

Integer

String

keys mapped_memory

String

Operations

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

String

mapped_memory

Integer

String

Integer

String

Integer

Operations

Integer

String

boolean

String

Part II Tutorials

records data in

Propert ies

organize

Traversal

navigates

ident ifies

Algorithm

expresses

Relat ionships

organize

records data in

Indexes

Relat ionships

m ap to

Propert ies

m ap fromorganize

Graph Database

m anages

Indexes

m anages

Relat ionships

records data in

m ap to

Propert ies

m ap from organize

Traversal

navigates

ident ifies

Algorithm

expresses

Figure 111 RDBMS

B3B5 B7

C1 C2C3

V1D2S2 V2V3V4D1S1

S1D2 S2S3

A Relat ionship

Start node

End node

Relat ionship type

Node loop

follows follows

William

blocks

follows

What How

A Property

Prim it ive

boolean

double

St ring

boolean truefalse

u0000 to uffff (0 to 65535)

Eclipse

NetBeans

Maven dependency

ltprojectgt

ltdependenciesgt

ltdependencygt

ltdependenciesgt

ltprojectgt

ltivysettingsgt

ltresolversgt

ltchain name=maingt

ltfilesystemgt

ltchaingt

ltresolversgt

ltivysettingsgt

ltdependenciesgt

EXAMPLE

firstNodedelete()

secondNodedelete()

txsuccess()

finally

txfinish()

graphDbshutdown()

USERS_REFERENCE

return node

httpwikineo4jorg )

RelTypesUSER )

int idToFind = 45

124 Traversal

DirectionOUTGOING )

depth() + =gt

Override

DirectionOUTGOING )

Get the admins

Get all groups

Override

return false

RoleRelsROOT

The Matrix

breadthFirst()

evaluator(

User roles

Get the admins

breadthFirst()

depthFirst()

Get all groups

breadthFirst()

nodes() )

breadthFirst()

evaluator(

Create a toy graph

Walk the path

new Evaluator()

Override

for ( Path path t )

1244 Social network

Simple social model

bull Person

bull StatusUpdate

depthFirst()

The code looks like

statusesremove( 0 )

firstnext()

sort()

return returnVal

Override

pathweight()

return result

return startTime

Part III Tools

Web Administration

Neo4j Shell

binneo4j-shell

neo4j-shell

neo4j-sh (0)$

Neo4j Shell

relationship

Neo4j Shell

$ set -t int age 29

Neo4j Shell

Override

outprintln( Types )

return null

Neo4j Shell

Current is (0)

set name Jon

send a cypher query

+----------------------+

1 rows 42 ms

where are we

name =[Jon]

ls -avr

Current is (1)

(0)--gt(1)

ls -avr

Appendix A Manpages

Manpages

COMMANDS

Manpages

REMOTE OPTIONS

LOCAL OPTIONS

neo4j-shell

Examples for local

Manpages

COMMANDS

Manpages

OPTIONS

Table of Contents

Introduction


2 Neo4j highlights




111 Server

112 Embedded


121 CPU

122 Memory

123 Disk

124 Filesystem

125 Software

13 Installation


14 Upgrading

141 Normal Upgrade

142 Special Upgrade









21 Caches in Neo4j


Configuration

212 Object cache

Configuration

Heap memory usage

22 JVM Settings






32 Isolation levels


34 Deadlocks

35 Delete semantics


41 Identifiers

42 Start

421 Node by id





43 Match

431 Related nodes







44 Where





445 Property exists

45 Return

451 Return nodes



454 Return property



46 Aggregation

461 COUNT

462 Count nodes

463 Count entities


465 SUM

466 AVG

467 MAX

468 MIN

47 Order by




474 Ordering null

48 Skip



49 Limit





512 Linux Service















56 Server Plugins





Chapter 6 REST API

61 Service root


62 Nodes

621 Create node


623 Get node


625 Delete node


63 Relationships









65 Node properties










67 Indexes








68 Traversals














611 Gremlin Plugin





612 Cypher Plugin

6121 Send a Query

Chapter 7 Indexing

71 Introduction

72 Create

73 Delete

74 Add

75 Remove

76 Update

77 Search

771 Get

772 Query


79 Scores



7111 Numeric ranges

7112 Sorting




7116 Caching

712 Batch insertion

7121 Best practices

713 Auto Indexing

7131 Configuration

7132 Search





81 Introduction


91 Architecture


921 Small

922 Medium

923 Large




101 Backup




102 Security


103 Monitoring

1031 JMX




Part II Tutorials














1131 Relationships

1132 Properties





Maven

Ivy

122 Hello world


124 Traversal

1241 The Matrix

1242 User roles


The Matrix

User roles


1244 Social network

Simple social model


Activity stream

125 Domain entities



Part III Tools


131 Dashboard tab

1311 Entity chart


132 Data tab

133 Console tab







1414 Read-only mode



143 Enum options

144 Filters

145 Node titles









1468 Traverse


14610 Indexing






Appendix A Manpages

neo4j

neo4j-shell

neo4j-coordinator


Documents

The Neo4j Manual v1.4