AN INTRODUCTION TO PYTHON AND GRAPH DATABASES WITH NEO4J Holger Spill Kiwi PyCon – 14 September 2014

http://lorenabarba.com/blog/

A GRAPH Node Relationship

https://wiki.cs.umd.edu/cmsc734_09/index.php David Bowie Defines Rock Royalty ANOTHER GRAPH

WHERE ARE GRAPHS USEFUL?  Social Network  Network Impact Analysis  Route Finding  Recommendations  Logistics  Access Control  Fraud Analysis  Securities and Debt  …

THE PROPERTIES GRAPH language:’Swedish’ open_source:true year:2007 by Nicole White - @_nicolemargaret

FROM SQL TO CYPHER

EXAMPLE: YOUTUBE IN SQL ID Name 1 Alice 2 Bob 3 Charles 4 David ID Name 1 Bob’s Gaming Channel 2 Bob’s Cute Dog 3 Cooking with Charles 4 David’s How-To Channel 5 Disco Dancing with David User ID Channel ID 2 1 2 2 3 3 4 4 4 5 USERS CHANNELS USERS_CHANNELS User ID Channel ID 1 3 1 4 2 3 2 5 3 1 USERS_SUBSCRIPTIONS

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel

CYPHER QUERY LANGUAGE .|'''', '|| | || || '|| ||` '||''|, ||''|, .|''|, '||''| || `|..|| || || || || ||..|| || `|....' || ||..|' .|| || `|... .||. , |' || '' .||

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH (c:Channel) RETURN c;

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH (u:User) RETURN u;

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH (bob:User {name:’Bob’}) RETURN bob;

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH (u:User)-[r:OPERATES]->(c:Channel) RETURN u,r,c;

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH p=(:User)-[:OPERATES]->(:Channel) RETURN p;

EXAMPLE: YOUTUBE IN A GRAPH name:’Alice’ name:’Bob’ name:’Charles’ name:’ David’ name:’Cooking with Charles’ name:’David’s How- To Channel’ name:’Disco Dancing with David’ name:’Bob’s Gaming Channel’ name:’Bob’s Cute Dog’ User Channel MATCH p=(:User {name:'Charles'})-[*1..4]-(:User {name:'David'}) RETURN p LIMIT 1;

CYPHER QUERY STRUCTURE MATCH (n:Label)-[:REL]->(m:Label) WHERE n.prop < 42 WITH n, count(m) as cnt, collect(m.attr) as attrs WHERE cnt > 12 RETURN n.prop, extract(a2 in filter(a1 in attrs WHERE a1 =~ "...-.*") | substr(a2,4,size(a2)-1)] AS ids ORDER BY length(ids) DESC LIMIT 10

PROS & CONS Strengths  Powerful data model, as general as RDBMS  Whiteboard friendly, flexible development  Fast, for connected data  Easy to query Weaknesses:  Sharding  Global Queries and Number Crunching  Binary Data / Blobs  Requires conceptual shift

READY, STEADY, GO START … or how to install Neo4j on Ubuntu  Start with a stock Ubuntu install  Install Oracle JDK7 (see askubuntu)  Download Neo4j Linux Community Edition  Follow the Neo4j installation instructions for Linux cd ; bin/neo4j start  Visit http://localhost:7474/browser/

READY, STEADY, GO START

MAKING FRIENDS www.neo4j.org www.python.org

PY2NEO  simple and pragmatic Python library  provides access via RESTful web services  no external dependencies  installation is straightforward  getting started is easy  actively maintained on GitHub by Nigel Small from py2neo import neo4j db_uri = "http://localhost:7474/db/data/" graph = neo4j.GraphDatabaseService(db_uri) neo4j.CypherQuery(graph, "Cypher goes here").run()

… AND ALTERNATIVES Object Graph Mapper (OGM) built on top of py2neo Neo4j Rest Client Object Graph Mapper (OGM) for Django. Use familiar Django models and queries against Neo4j. Python persistence framework for graph databases

REST API :GET /dbdata { "extensions": {}, "node": "http://localhost:7474/db/data/node", "node_index": "http://localhost:7474/db/data/index/node", […] "http://localhost:7474/db/data/schema/constraint", "transaction": http://localhost:7474/db/data/transaction", "node_labels": "http://localhost:7474/db/data/labels", "neo4j_version": "2.1.4” }

CURRENT RELEASE Neo4j 2.1.4 4 September, 2014 Community and Enterprise Edition  Import CSV Files with Cypher  Dense nodes support  New Cypher functionality  Official support for OpenJDK 7  ... and more http://neo4j.com/release-notes/neo4j-2-1-4/

JOIN THE CONVERSATION bit.ly/neo4j-google @neo4j #neo4j www.stackoverflow.com neo4j.meetup.com >>> Neo4j version, programming language, driver name, query language <<<

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