An Introduction to Neo4j

Neo4j Product Overview

NOSQL, The Web And The Enterprise

private static enum ExampleRelationshipTypes implementsRelationshipType{ EXAMPLE}GraphDatabaseService graphDb = new EmbeddedGraphDatabase( DB_PATH );registerShutdownHook( graphDb );graphDb.shutdown();

Transaction tx = graphDb.beginTx();try{ Node firstNode = graphDb.createNode(); firstNode.setProperty( NAME_KEY, "Hello" ); Node secondNode = graphDb.createNode(); secondNode.setProperty( NAME_KEY, "World" ); firstNode.createRelationshipTo( secondNode, ExampleRelationshipTypes.EXAMPLE ); String greeting = firstNode.getProperty( NAME_KEY ) + " " + secondNode.getProperty( NAME_KEY ); System.out.println( greeting ); tx.success();}finally{ tx.finish();}

private void printFriends( Node person ){ Traverser traverser = person.traverse( Order.BREADTH_FIRST, // StopEvaluator.END_OF_GRAPH, // Graph ReturnableEvaluator.ALL_BUT_START_NODE, MyRelationshipTypes.KNOWS, // ”KNOWS” Direction.OUTGOING ); // for ( Node friend : traverser ) { // Node ”name” System.out.println( friend.getProperty( "name" ) ); }}

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private static Traverser findHackers( final Node startNode ){ TraversalDescription td = Traversal.description() .breadthFirst() .relationships( RelTypes.CODED_BY, Direction.OUTGOING ) .relationships( RelTypes.KNOWS, Direction.OUTGOING ) .evaluator( Evaluators.returnWhereLastRelationshipTypeIs(RelTypes.CODED_BY ) ); return td.traverse( startNode );}Traverser traverser = findHackers( getNeoNode() );int numberOfHackers = 0;for ( Path hackerPath : traverser ){ System.out.println( "At depth " + hackerPath.length() + " => " + hackerPath.endNode() .getProperty( "name" ) );}

Traverser traverser = person.traverse( Order.BREADTH_FIRST, StopEvaluator.END_OF_GRAPH, ReturnableEvaluator.ALL_BUT_START_NODE, MyRelationshipTypes.KNOWS, Direction.OUTGOING );for ( Node friend : traverser ){...}

/* 1. Begin a transaction. 2. Operate on the graph. 3. Mark the transaction as successful (or not). 4. Finish the transaction.*/Transaction tx = graphDb.beginTx();try{ ... // any operation that works with the node space tx.success();}finally{ tx.finish();}

Graph Databases and Endogenous Indices name property indexviews property index gender property index name=neo4j views=56781 page_rank=0.023 cites cites name=tenderlove gender=male created created created date=2007/10 cites follows follows created name=peterneubauer follows name=graph_blog follows views=1000 follows created name=ahzf name=twarko age=30

GraphDatabaseService graphDb = newEmbeddedGraphDatabase( "path/to/neo4j-db" );IndexService index = new LuceneIndexService( graphDb );Node andy = graphDb.createNode();Node larry = graphDb.createNode();andy.setProperty( "name", "Andy Wachowski" );andy.setProperty( "title", "Director" );larry.setProperty( "name", "Larry Wachowski" );larry.setProperty( "title", "Director" );index.index( andy, "name", andy.getProperty( "name" ) );index.index( andy, "title", andy.getProperty( "title" ) );index.index( larry, "name", larry.getProperty( "name" ) );index.index( larry, "title", larry.getProperty( "title" ) ); http://wiki.neo4j.org/content/Indexing_with_IndexService

// Return the andy node.index.getSingleNode( "name", "Andy Wachowski" );// Containing only the larry nodefor ( Node hit : index.getNodes( "name", "Larry Wachowski" ) ){ // do something}// Containing both andy and larryfor ( Node hit : index.getNodes( "title", "Director" ){ // do something} http://wiki.neo4j.org/content/Indexing_with_IndexService

IndexService index = // your LuceneFulltextIndexServiceindex.getNodes( "name", "wachowski" ); // --> andy and larryindex.getNodes( "name", "andy" ); // --> andyindex.getNodes( "name", "Andy" ); // --> andyindex.getNodes( "name", "larry Wachowski" ); // --> larryindex.getNodes( "name", "wachowski larry" ); // --> larryindex.getNodes( "name", "wachow* andy" ); // --> andy and larryindex.getNodes( "name", "Andy" ); // --> andyindex.getNodes( "name", "andy" ); // --> andyindex.getNodes( "name", "wachowski" ); // --> andy and larryindex.getNodes( "name", "+wachow* +larry" ); // --> larryindex.getNodes( "name", "andy AND larry" ); // -->index.getNodes( "name", "andy OR larry" ); // --> andy and larryindex.getNodes( "name", "Wachowski AND larry" ); // --> larry http://wiki.neo4j.org/content/Indexing_with_IndexService

of a spatial, 2D-index that is explicitly14 Marko A.within a Peter Neubauer modeled Rodriguez and 1 2 In order to demonstrate how a quadtree index can be represented anpatial analysis makes use of advanced indexing structuresis represents a quadtreeset is diagrammed i versed, a toy graph data set presented. This data ure 8. The top half of Figure 8 index (vertices 1-9) [4, 17]. Quadtrees partition a two-dimensional plane into sed upon the spatial density of the points being indexed. type=quadow space is partitioned as the density of points increases bl=[0,0] tr=[100,100] e index. 1 sub sub type=quad type=quad type=quad bl=[0,0] 2 3 bl=[50,25] 4 bl=[50,0] tr=[50,100] tr=[75,50] tr=[100,100] type=quad type=quad bl=[0,0] bl=[50,50] tr=[50,50] tr=[100,100] type=quad type=quad bl=[0,50] 5 6 9 7 8 bl=[50,0] tr=[50,100] tr=[100,50] type=quad [0,100] 1 bl=[50,25] [100,100] tr=[62,37] g f a b e 5 7 9 bl=[25,20] d 3 h c tr=[90,45]artition of a plane. This ﬁgure is an adaptation of a public id courtesy of David Eppstein. 6 2 4 8 [100,0] [0,0] motivations behind this article is to stress the A quadtree index ofof space that contains points of interest. The in Fig. 8. importance a

TraversalDescription description = Traversal.description() .breadthFirst() .relationships(Relationships.PAIRED, Direction.OUTGOING) .evaluator(Evaluators.excludeStartPosition());description.traverse( startNode ); // Retrieves the traverserstart programmer=(3) match (programmer)-[:PAIRED]->(pair) return pairstart programmer=(3) match (programmer)-[:PAIRED]->(pair)where pair.age > 30 return pair, count(*) order by ageskip 5 limit 10

[InComing/Outgoing relationships] # All nodes that A has outgoing relationships to. > start n=node(3) match (n)-->(x) return x ==> Node[4]{name->"Bossman"} ==> Node[5]{name->"Cesar"} > start n=node(3) match (n)<--(x) return x ==> Node[1]{name->David"}[Match by relationship type]# All nodes that are Blocked by A.> start n=node(3) match (n)-[:BLOCKS]->(x) return x==> Node[5]{name->"Cesar"}[Multiple relationships]# The three nodes in the path.> start a=node(3) match (a)-[:KNOWS]->(b)-[:KNOWS]->(c) return a,b,c==> a: Node[3]{name->"Anders"}==> b: Node[4]{name->"Bossman"}==> c: Node[2]{name->"Emil"}

[Shortest path]# : find the shortest path between two nodes, as long as the path is max 15relationships long. Inside of the parenthesis you can write> start d=node(1), e=node(2) match p = shortestPath( d-[*..15]->e ) return p==> p: (1)--[KNOWS,2]-->(3)--[KNOWS,0]-->(4)--[KNOWS,3]-->(2)

[Count/ Group Count]> start n=node(2) match (n)-->(x) return n, count(*)# The start node and the count of related nodes.==>n: Node[2]{name->"A",property->13}count(*): 3> start n=node(2) match (n)-[r]->() return type(r), count(*)# The relationship types and their group count.==>TYPE(r): KNOWScount(*): 3

[SUM/AVG/MAX/COLLECT]> start n=node(2,3,4) return sum(n.property)==> 90> start n=node(2,3,4) return avg(n.property)==> 30.0> start n=node(2,3,4) return max(n.property)==> 44> start n=node(2,3,4) return collect(n.property)==> List(13, 33, 44)

http://www.graph-database.org	23892
http://graphdb.jp	1765
http://paper.li	104
http://graph-databases.org	43
http://translate.googleusercontent.com	34
http://webcache.googleusercontent.com	29
http://a0.twimg.com	21
http://abtasty.com	12
http://us-w1.rockmelt.com	10
http://tweetedtimes.com	8
http://www.graph-databases.org	8
https://twitter.com	4
http://www.slideshare.net	2
http://prlog.ru	1
http://fujohnwang.github.com	1
http://www.graph-database.org&_=1333885391046 HTTP	1
http://demo.apostrophenow.org	1
http://www.graph-database.org.sixxs.org	1

An Introduction to Neo4j

by Takahiro Inoue on Oct 07, 2011

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