Application Modeling With Graph Databases - Relationships are cool!

Application Modeling with Graph Databases Relationships are cool!

Lars Martin, JUG Saxony Day, 04.04.2014


Developer, Architect, Consultant

Java Enterprise, Eclipse, Continuous

Entrepreneur since 1998

Whos the guy?

Agenda

Status Quo

SQL Join Hell

Graph Basics

Application Modeling



Status Quo

http://db-engines.com/en/ranking_definition


SQL Join Hell (1)

Customer Id Name Address

1 Robert 3 2 Lars 7 3 Michael 23

Address Id Location

3 Berlin 4 Munich 7 Dresden

23 Leipzig

CustomerAddress CId AId

1 3 2 7 2 8 3 23

Address Id Location

3 Berlin 7 Dresden 8 New York

23 Leipzig

Address Id Customer Location

3 1 Berlin 7 2 Dresden 8 2 New York

23 3 Leipzig

Customer Id Name

1 Robert 2 Lars 3 Michael

1:1 Relationship

m:n Relationship

1:n Relationship

Customer Id Name

1 Robert 2 Lars 3 Michael


SQL Join Hell (2)


SQL Join Hell (3)

all JOINs are executed every time you query (traverse) the relationship

executing a JOIN means to search for a key in another table

with Indices executing a JOIN means to lookup a key B-Tree Index: O(log(n)) more entries more lookups slower JOINs


Graphs a Crash Course in Coolness

G = (V, E) G

raph

Vert

ex

Edge

h"p://de.wikipedia.org/wiki/Graph_(Graphentheorie)



Vertices unique identifier outgoing edges incoming edges key/value pairs Edges unique identifier start vertex end vertex type key/value pairs

https://github.com/tinkerpop/gremlin/wiki/Defining-a-Property-Graph

index-free adjacency ( O(1))


Real World Graphs (1)

maps closely to the data model noun = vertex verb = edge



whiteboard friendly


Social: Facebook, Twitter, LinkedIn Recommendations: Amazon, MovieDB

Logistics: Package Routing

Financial: Fraud Detection Software: Dependency Management

Authorization & Access Control:



Social: Facebook, Twitter, LinkedIn Recommendations: Amazon, MovieDB

Logistics: Package Routing

Financial: Fraud Detection Software: Dependency Management

Authorization & Access Control:


our area of activities



Spring Data projects.spring.io/spring-data

Spring Data Neo4j supports property graph features

XO - eXtended Objects github.com/buschmais/xo

Lightweight Datastore-agnostic ORM Implementation of Composite Pattern Interface based (no POJOS), multiple inheritance XO-Neo4j supports property graph features



@Labelpublic interface User { @Indexed(unique = true) String getName(); void setName(String name); @Relation("POSTED") @Outgoing Set getTweets(); @Relation("FOLLOWS") @Outgoing Set getFollowing();}

@Labelpublic interface Tweet { @Indexed(unique = true) long getTweetId(); void setTweetId(long id); String getText(); void setText(String text); @Relation("POSTED") @Incoming User getSender(); void setSender(User sender); @Relation("MENTIONED") @Outgoing Set getMentions();

}

MATCH(me)-[:POSTED]->(tweet)-[:MENTIONED]->(user)

WHEREme.name = 'Neo4j AND NOT (me)-[:FOLLOWS]->(user)

WITHuser ORDER BY user.name

RETURNDISTINCT user



@ResultOf@Cypher("MATCH (me)-[:POSTED]->(tweet)-[:MENTIONED]->(user) WHERE id(me) = id({this}) AND NOT (me)-[:FOLLOWS]->(user) WITH user ORDER BY user.name RETURN DISTINCT user")Result suggestFriends();

Demo



Relational Database tabular data structures

Graph Database

connected data, esp. multiple degrees

schema-less



A relational database may tell you the average age of everyone in this place

but a graph database will tell you who is most likely to buy you a beer.

SMB GmbH Plauenscher Ring 21 D-01187 Dresden

Dipl.-Inf. Lars Martin +49-(0)173-64 24 461 [email protected]

Documents

Application Modeling With Graph Databases - Relationships are cool!