This document discusses Neo4j, a graph database that is well-suited for data modeling problems involving complex relationships and connections. It provides an introduction to graph databases as an alternative to relational databases for certain tasks, describes some example queries in Cypher for Neo4j, and shows how Neo4j can be used to calculate the "Bacon number" for actors based on the movies they have appeared in.

1. N E O 4 J
A L I T T L E B I T O F M A T H A N D M A G I C

2. G R A P H S A R E E V E RY W H E R E !

3. O T H E R Q U E S T I O N S
• What film should I see tonight?
• Where should I have a lunch?
• How can I get there?
• How can I get the cheapest tickets for a flight?

4. U S U A L LY W E U S E R E L AT I O N S

5. Relational DB
Graph

6. G R A P H
D ATA B A S E S
A LT E R N A T I V E I S

7. G R A P H D ATA B A S E S
• Neo4j
• FlockDB
• AllegroGraph
• GraphDB
• InfiniteGraph
• OrientDB

8. I S I T R E A L LY A H I P S T E R T H I N G ?
• Java
• Community/Enterprise edition
• ASID compliant, cluster support,
runtime failover
• Used by many companies

9. C Y P H E R
• It’s like SQL but for graphs
MATCH (user)-[:friend]->(follower)
WHERE user.name IN ['Joe', 'John', 'Sara', 'Maria', 'Steve']
AND follower.name =~ ’S.*'
LIMIT 5
RETURN user.name, follower.name

10. O K , N E O 4 J I S F O R TA S K S
W H E R E D ATA I S A G R A P H .
( W H E R E Y O U H A V E A L O T O F J O I N S )

11. Q U I C K S TA RT
• http://neo4j.com/download/
• bin/neo4j start
• locahost:7474

12. S O M E E X A M P L E S
MATCH ()-[r:ACTED_IN]->() RETURN r
MATCH (gene:Person)-[:ACTED_IN]->(m),
(other)-[:ACTED_IN]->(m)
WHERE gene.name="Gene Hackman"
RETURN DISTINCT other;
MATCH (a:Person)-[:ACTED_IN]->(m)
RETURN a.name, count(m)
ORDER BY count(m) DESC
LIMIT 10;
MATCH (tom:Person)-[:ACTED_IN]->()<-[:ACTED_IN]-(a:Person)
WHERE tom.name="Tom Hanks"
AND a.born < tom.born
RETURN a.name;

13. B A C O N N U M B E R

14. MATCH (kevin:Person { name:"Kevin Bacon" }),
(al:Person { name:"Al Pacino" }), p =
shortestPath((kevin)-[*..15]-(al)) RETURN p
MATCH
p=shortestPath((kevin:Person)-[r:ACTED_IN*]-(actor))
WHERE
kevin.name='Kevin Bacon' AND actor.name='Al Pacino'
RETURN
length([m in nodes(p) WHERE m:Movie]) as BaconNumber,
[m in nodes(p) WHERE m:Movie | m.title] as Movies,
[a in nodes(p) WHERE a:Person | a.name][1..-1] as KnowsActors

15. Q & A
Q&A