An Introduction to Solr

Searching with SolrTom Hill

t.hill@worldware.comeBig Java SIG, June 18th, 2008

Tonight's Talk

•Tonight's Talk should run about 1 1/2 hours

•About Solr

•Background & overview

•Installing & Bringing Up Solr

•Rest Interface & Java Client

•Configuring Solr

Why Implement Search?

•Does your site need search?

•Do you need to implement it, or is Google enough?

• Just text or Structured Data?

• Do you need to control ranking?

What is Solr?

•Web application for text search

•A wrapper around Apache Lucene

•Lucene is a library (.jar file)

•Solr is a web app (.war file)

•Written at CNet, now at Apache

What is Lucene?

•Text search library in Java

•Fast, feature rich.

•Written by Doug Cutting

•Active Apache development community

•Versions also in C++, C#, Ruby, Python, Delphi, Lisp, etc...

Why Solr?

•Reliable

•Fast

•Supported

•Open Source

•Tunable Scoring

Solr Versions

•Current Version is 1.2

• A year old

• 1.3 is coming "sometime"

•Large number of features in HEAD

• Use the latest from subversion for new projects

Alternatives to Solr

•Just Use Google

•Use Lucene

•Use Your Database

•Commercial Libraries

•Write your own

What Solr is Not

•A replacement for a relational database

•An embedded database*

•Fully cross platform :-(

• Replication depends on unix FS

• Admin scripts are bash(minor)

Solr Sites

•CNet (Reviews & Products)

•Internet Archive (Collections)

•Netflix (Movies)

•Zvents (Events)

•StripSearch.ws (Comics)

•And many more

Features

Here's a quick look at some of the features of Solr,as implemented on Zvents.com

Faceted Navigation

Groups the results by categoryCan do multiple facets at once Returns matching counts

Additional Constraints

Synonyms, etc.

Solr Overview

Simple WebappWeb Servers[1..n]Web Servers[1..n]Database MasterDatabase Master

Database Slaves[0..n]Database Slaves[0..n]

Solr MasterSolr Master

Solr Slaves[0..n]Solr Slaves[0..n]

Scaling Solr

•Master/Slave architecture

•Writes to master/reads to slaves

•Replication: Periodic transfers, not continuous

•Rsync

Updates

•Updates flush caches, bad for performance

•Master therefor much slower than slaves

• So send all queries to slaves

•Depends on your update rates

Solr's Data Model

• Solr maintains a collection of documents

• A document is a collection of fields & values

• A field can occur multiple times in a document

• Documents are immutable.

• They can be deleted, and a new version added, however.

Querying

•Http request

• http://localhost:8080/comix/select/?q=java

Solr Query Syntax

•Lucene Query Syntax + a bit

•paris

•city:paris

•title:"The Right Way" AND text:go

•id:[* TO *]

Solr Query Syntax II

•-inStock:false

•te?t

•theat*

•te*t

•test~

Using Solr

•Getting data into Solr

•Getting data out of Solr

Getting Data Into Solr•POST it.

<add> <doc> <field name="employeeId">05991</field> <field name="office">Bridgewater</field> <field name="skills">Perl</field> <field name="skills">Java</field> </doc> [<doc> ... </doc>[<doc> ... </doc>]]</add>

Getting Data Into Solr•POST it.

<add> <doc> <field name="employeeId">05991</field> <field name="office">Bridgewater</field> <field name="skills">Perl</field> <field name="skills">Java</field> </doc> [<doc> ... </doc>[<doc> ... </doc>]]</add>

Getting Data Into Solr•POST it.

<add> <doc> <field name="employeeId">05991</field> <field name="office">Bridgewater</field> <field name="skills">Perl</field> <field name="skills">Java</field> </doc> [<doc> ... </doc>[<doc> ... </doc>]]</add>

Committing

•Nothing shows up in the index until you commit

•You can just POST <commit/> to http://host:port/solr/update

Getting Data Outhttp://localhost:8080/comix/select/?q=data&indent=on<response><lst name="responseHeader"> <int name="status">0</int> <int name="QTime">0</int> <lst name="params"> <str name="indent">on</str> <str name="q">data</str> </lst></lst><result name="response" numFound="2" start="0"> <doc> <str name="id">strip.3136</str> <str name="release_date">1992-05-07</str> <date name="timestamp">2008-02-28T10:06:01.682Z</date> <str name="type">strip</str> </doc> </result></response>

Getting Data Outhttp://localhost:8080/comix/select/?q=data&indent=on<response><lst name="responseHeader"> <int name="status">0</int> <int name="QTime">0</int> <lst name="params"> <str name="indent">on</str> <str name="q">data</str> </lst></lst><result name="response" numFound="2" start="0"> <doc> <str name="id">strip.3136</str> <str name="release_date">1992-05-07</str> <date name="timestamp">2008-02-28T10:06:01.682Z</date> <str name="type">strip</str> </doc> </result></response>

Getting Data Outhttp://localhost:8080/comix/select/?q=data&indent=on<response><lst name="responseHeader"> <int name="status">0</int> <int name="QTime">0</int> <lst name="params"> <str name="indent">on</str> <str name="q">data</str> </lst></lst><result name="response" numFound="2" start="0"> <doc> <str name="id">strip.3136</str> <str name="release_date">1992-05-07</str> <date name="timestamp">2008-02-28T10:06:01.682Z</date> <str name="type">strip</str> </doc> ... </result></response>

Getting Data Outhttp://localhost:8080/comix/select/?q=data&indent=on{ "responseHeader":{ "status":0, "QTime":1, "params":{

"wt":"json","rows":["1", "1"],"start":"0","indent":"on","q":"data","version":"2.2"}},

"response":{"numFound":2,"start":0,"docs":[{ "feature_id":"3", "release_date":"1992-05-07", "id":"strip.3136", "timestamp":"2008-02-28T10:06:01.682Z"}]

}}

JSON format

Debug Query Option

•Add &debugQuery=on to request params

•Returns parsed form of query

<str name="rawquerystring">c.i.a</str><str name="querystring">c.i.a</str><str name="parsedquery">PhraseQuery(text:"c i a")</str><str name="parsedquery_toString">text:"c i a"</str>

Debug Query Option II

•Add &debugQuery=on to request params

•Returns scoring information

<str name="id=strip.2781,internal_docid=29854"> 2.6219895 = (MATCH) fieldWeight(text:calvin in 29854), product of: 1.0 = tf(termFreq(text:calvin)=1) 2.6219895 = idf(docFreq=6222) 1.0 = fieldNorm(field=text, doc=29854)</str> <str name="id=strip.4078,internal_docid=31151"> 2.6219895 = (MATCH) fieldWeight(text:calvin in 31151), product of: 1.0 = tf(termFreq(text:calvin)=1) 2.6219895 = idf(docFreq=6222) 1.0 = fieldNorm(field=text, doc=31151)</str>

Deleting Data

<delete><id>35</id></delete><delete><query>city:paris</query></delete>

•POST

Command Line Control

curl http://localhost:8983/solr/update -H "Content-type: text/xml" --data-binary '<commit/>'<?xml version="1.0" encoding="UTF-8"?><response><lst name="responseHeader"><int name="status">0</int>

<int name="QTime">20</int></lst></response>

Solr in 3 minutes!

•Download Solr from Apache•Untar•"ant example"•Start the example app•Load data into Solr•Query

Solr in Ten Minutes

<Context docBase="/var/solr/apache-solr-1.2.0.war" debug="0" crossContext="true" > <Environment name="solr/home" type="java.lang.String" value="/var/solr" override="true" /></Context>

•Copy Solr's example/solr dir to /var/solr •Edit schema.xml and solrconfig.xml•Load data into Solr

•In $CATALINA_HOME/conf/Catalina/localhost/foo.xml

Directory Layout

•${solr.home}/conf

•schema.xml

•solrconfig.xml

•${solr.home}/data

•${solr.home}/logs

•${solr.home}/bin

Java Solr Client•Called SolrJ

•Not in Solr 1.2.

• I grabbed from the HEAD from svn

• Works with Solr 1.2

•Add/Delete/Query/Commit/Optimize

Adding Docs w/SolrJGiven Map<String, String> fields;

CommonsHttpSolrServer server = new CommonsHttpSolrServer(url);

SolrInputDocument doc=new SolrInputDocument();for (Map.Entry<String, String> e :fields.entrySet()){ doc.addField(e.getKey(), e.getValue());}

UpdateResponse res = server.add( doc);

Deleting Docs w/SolrJ

CommonsHttpSolrServer server = new CommonsHttpSolrServer(url);

UpdateResponse res;

res =server.deleteById("100");res =server.deleteByQuery("city:paris");

Simple QueryCommonsHttpSolrServer server= new CommonsHttpSolrServer(url);

SolrQuery query = new SolrQuery();

query.setQuery("dance");

QueryResponse rsp = server.query(query);

More Interesting Query

CommonsHttpSolrServer server = new CommonsHttpSolrServer(url);

SolrQuery query = new SolrQuery();query.setQuery("dance");query.setFacet(true);query.addFacetField("city");query.setFacetMinCount(1);query.addSortField( "price", SolrQuery.ORDER.asc );QueryResponse rsp = server.query(query);

Query Responses

QueryResponse qr = server.query(query);SolrDocumentList docs = qr.getResults();List<FacetField> lf = qr.getFacetFields();for (FacetField ff: lf) { String fieldName = ff.getName(); List<FacetField.Count> lc = ff.getValues(); for (FacetField.Count c: lc) { String countName = c.getName();long count = c.getCount();

}}

Other Commands

•Commit•server.commit()

•Optimize•server.optimize()

•Not too complicated!

Request Handlers•Request handler define how the

query is processed.

•Two main types

•StandardRequestHandler

•DisMaxRequestHandler

•You can implement your own

•Changing in Solr 1.3

"Standard" Request Handler

•Accepts Solr Query Syntax

•I tend to use it for my queries, not user queries.

DisMaxRequestHandler

•Recommended for user queries

•Allows simple users keywords to be applied to multiple fields, with weighting.

•Boost Functions

•Boost Queries

Boost Functions

•Allow you to influence scoring at run time

•Computationally Expensive!

•Really useful for tuning scoring

•linear(x,2,4) returns 2*x+4

• x is a field

The Solr Schema

•schema.xml

•Defines types used in this webapp

•Defines the fields and their types

•Defines "copyFields"

•READ THE EXAMPLE SCHEMA.XML

Types•Types define processing for a field

•How the words are split (Whitespace? Punctuation? CIA != C.I.A.)

•Stemming

•Case Folding, etc

•Predefined date, int, float, etc

•c

Analysis: Index and Query Time

•Types have two modes

•Index Time

•Query Time

Simple Text Field

<fieldType name="text" class="solr.TextField" positionIncrementGap="100"> <analyzer type="index"> <tokenizer class="solr.WhitespaceTokenizerFactory"/> <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt"/></analyzer><analyzer type="query"><tokenizer class="solr.WhitespaceTokenizerFactory"/><filter class="solr.SynonymFilterFactory" synonyms="synonyms.txt" ignoreCase="true" expand="true"/><filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt"/></analyzer></fieldType>

Analysis & Facets

•Make sure to use an untokenized field for faceting.

•"San Jose" != "San" "Jose"

Fields

•Elements of a document

•Both predefined & dynamic

•Fields may occur multiple times

•Maybe indexed and/or stored

Example Fields

<field name="id" type="string" indexed="true" stored="true" required="true" /><field name="name" type="text" indexed="true" stored="true"/><field name="alphaNameSort" type="alphaOnlySort" indexed="true" stored="false"/>

Copy Fields

•Two main uses

•To analyze a field in two different ways

•To concatenate fields

The Solr Config File

•solrconfig.xml

•Defines request handlers, defaults, caches,

•Read the example solrconfig.xml

Configuring DisMax

•Parameter defaults set in solrconfig.xml

•Can be overridden in each request

•Except for params labeled invariant

DisMax Config Example

<requestHandler name="dismax" class="solr.DisMaxRequestHandler" > <lst name="defaults"> <str name="echoParams">explicit</str> <float name="tie">0.01</float> <str name="qf"> text^0.5 features^1.0 name^1.2 sku^1.5 id^10.0 manu^1.1 cat^1.4 </str> <str name="pf"> text^0.2 features^1.1 name^1.5 manu^1.4 manu_exact^1.9 </str>... </requestHandler>

DisMax Config Example

<requestHandler name="dismax" class="solr.DisMaxRequestHandler" > ... <str name="bf"> ord(poplarity)^0.5 recip(rord(price),1,1000,1000)^0.3 </str> <str name="fl"> id,name,price,score </str>... </requestHandler>

DisMax Config Example

<requestHandler name="dismax" class="solr.DisMaxRequestHandler" > ... <str name="mm"> 2&lt;-1 5&lt;-2 6&lt;90% </str> <int name="ps">100</int> <str name="q.alt">*:*</str> </lst> </requestHandler>

Wrap Up

Resources

• Solr http://lucene.apache.org/solr/

• wiki, mailing list, jira (bugs/features)

• Lucene http://lucene.apache.org/

Lucene In Action

Building Search Applications with Lucene, lingpipe and Gate

Manu Konchady

Other Presentations

• Yonik Seely's Solr & Lucene

• http://people.apache.org/~yonik/presentations/

• Slideshare.net

• Search for solr, or search for lucene

Thanks!

Thanks for coming.

Feel free to email me if you have questions about Solr

Tom Hillt.hill@worldware.com

Extra Slides

Things I didn't have time for in the presentation.Some of them unfinished.

Search Engines are not the Same as

Users

•Search engines have different usage patterns than users

Response Writers

• http://localhost:8983/solr/select/?q=text_t%3Atiger&version=2.2&start=0&rows=10&indent=on&wt=ruby

• http://localhost:8983/solr/select/?q=text_t%3Atiger&version=2.2&start=0&rows=10&indent=on&wt=xml

Explain

•Just why did the documents come up in that order?

Data Matters

•Gigo

•The better the data is, the better the search will be.

Watch Your Caches

•Just like any other app, check your statistics

•What's the hit rate for your caches?

Setting Up Replication

•Run rsyncd on the master

•Run snapshot on the master at intervals

•Run snappuller on the slaves at (different) intervals.

•Scripts don't print errors!

•Check the logs

•Use bash -xv

Autowarming•Runs after an update to the index

•Updates flush caches

•Runs some queries to populate caches again

•Can be a problem, with frequent updates

•Don't autowarm master, if updating lots

Tour Of Solr's Web UI

Programming Collective Intelligence

A Really Fun Book

Geographic Searching•Local Lucene & Local

Solr•http://locallucene.wiki.sourceforg

e.net•There's also geolucene, but it's not being actively developed, as far as I can tell.•http://www.gossamer-threads.com/lists/lucene/java-dev/53378

http://localhost:8983/solr/admin/stats.jsp#update

Are there commits pending?

http://localhost:8983/comix/admin/analysis.jsp?name=text&val=wi-fi

Analysis Explanation