This document introduces graph databases and Neo4j. It discusses different database types and how graph databases are better suited to store connected data compared to relational databases. It provides an overview of Neo4j's core concepts like nodes, relationships, and properties. It also demonstrates how to query graph data using the Cypher query language, including finding friends, friends of friends, and calculating Bacon numbers. Resources for learning more about Neo4j and Cypher are also listed.

1. INTRODUCTION TO GRAPH
DATABASES WITH NEO4J
Brant Boehmann
@tbrantb

2. About Me
- ~20 Years Dev Experience
- Java/JVM Specialist
- Lead Software Engineer @ScrippsNet
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3. Outline
- DB Types
- What is a GraphDB
- RDBMS vs GraphDB
- Neo4J
- Cypher
- Neo4J Console
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4. Multiple DB Types
- Relational
- Oracle, MS-SQL, PostgreSQL, MySQL, ...
- Columnar
- GreenPlum, RedShift, ...
- Key-Value
- Dynamo, Riak, ...
- Document
- MongoDB, CouchDB, ...
- Graph
- Neo4J, Titan, OrientDB, ...
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5. Which DB type is right?
- Data Size
- Data structure
- Access Patterns
- Write Patterns
- Performance Requirements
- Consistency Requirements
- Degree of Data Connectedness
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6. Remember Graph Basics
- Node (Vertex)
- Relationship (Edge)
- Direction
- Path
A
D
B
C E
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7. Turn a Graph into a DB
- Node Labels
- Relationship Type
- Properties
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8. Shoehorn into RDBMS Attempt #1
- Convert a Graph to Table
- Adjacency Matrix
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9. Shoehorn into RDBMS Attempt #1
- Adjacency Matrix Doesn’t fit in RDBMS table :(
- Why?
- Schema / Static Columns
- Column growth
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10. Shoehorn into RDBMS Attempt #2
- Join Table
- Many-To-Many
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11. Who are Bob’s Friends
Pretty Simple
SELECT p2.id, p2.name
FROM person p1
JOIN person_relationship rel
ON p1.id = rel.start_person_id
AND p1.id = 1 --Bob
AND rel.relationship_type=1 --Friend
JOIN person p2
ON p2.id = rel.end_person_id
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12. Who are the Friends of Bob’s Friends?
SELECT p3.id, p3.name
FROM person p1
JOIN person_relationship rel1
ON p1.id = rel1.start_person_id
AND p1.id = 1 --Bob
AND rel1.relationship_type = 1 --Friend
JOIN person p2
ON p2.id = rel1.end_person_id
JOIN person_relationship rel2
ON p2.id = rel2.start_person_id
AND rel2.relationship_type = 1 --Friend
JOIN person p3
ON p3.id = rel2.end_person_id
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13. Bob’s Friends’ Friends’ Friends to the N
Do I have to?
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14. What is Bob’s Bacon # ?
?
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15. Not all problems
are well suited
for RDBMS
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16. How do Graph DBs do this better?
- RDBMS uses joins & table/index scans
- Native vs Non-Native GraphDB
- “Index Free Adjacency”
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17. Popular GraphDB Use Cases
- Social Networks
- Fraud Detection
- Recommendation Engines
- IAM
- Master Data Management (MDM)
- Network Ops
- Content/Asset Management
- Journalism (see Panama Papers)
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18. Algorithms/Concepts
- Shortest Path
- A*
- Triadic Closures
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19. Neo4J
- Labeled Property Graph
- Native Graph DB w/Index Free Adjacency
- JVM Based
- Fully ACID
- All relationships are directed *
- Schema-less, Schema-optional
- Embedded, Single Instance Server, HA Cluster
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20. Neo4J APIs
- Embedded Java API
- HTTP API
- Drivers/Bolt Protocol
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21. Cypher
- Declarative Graph Query Language
- Originated at Neo Technology
- Standardizing at OpenCypher.org
- Ascii Art-ish
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22. Ascii Art-ish ?
- () look like circles or nodes
- --, -->, <-- look like relationships or edges
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MATCH (a)-->(b)
WHERE a.name = 'Bob'
RETURN b

23. MATCH Clause
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MATCH (a)-->(b)
MATCH (a)-[:FRIEND]->(b)
MATCH (a)<-[:FRIEND]-(b)
MATCH (a)-[:FRIEND]-(b)

24. MATCH Clause with Labels
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MATCH (p:Person)-[:DIRECTED]->(m:Movie)
MATCH (a:Person)-[:ACTED_IN]->(m:Movie)<-[:DIRECTED]-(d:Person)

25. WHERE
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MATCH (p:Person)-[:DIRECTED]->(m:Movie)
WHERE p.name = 'Ron Howard'
AND p.born < 1955
MATCH (p:Person {name: 'Ron Howard'})-[:DIRECTED]->(m:Movie)

26. RETURN, ORDER BY, LIMIT
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MATCH (p:Person {name: 'Ron Howard'})-[:DIRECTED]->(m:Movie)
RETURN m.title, m.released, m.tagline
ORDER BY m.title
LIMIT 3

27. Overall Read Query Structure
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[MATCH WHERE]
[OPTIONAL MATCH WHERE]
[WITH [ORDER BY] [SKIP] [LIMIT]]
RETURN [ORDER BY] [SKIP] [LIMIT]

28. CREATE
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CREATE (matrix:Movie {title:'The Matrix', released:1999})
CREATE (keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (keanu)-[:ACTED_IN]->(matrix)
MATCH (matrix:Movie {title:'The Matrix'}),
(keanu:Person {name:'Keanu Reeves'})
CREATE (keanu)-[:ACTED_IN]->(matrix)

29. UPDATE
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MATCH (matrix:Movie {title:'The Matrix'}),
(keanu:Person {name:'Keanu Reeves'})
SET matrix.tagline = 'Follow the White Rabbit',
keanu.born = 1900
RETURN matrix, keanu //optional

30. DELETE
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MATCH (p:Person{name: 'Keanu Reeves'})
DELETE p
MATCH (p:Person{name: 'Keanu Reeves'})-[r]-()
DELETE r, p
MATCH (p:Person{name: 'Keanu Reeves'})
DETACH DELETE n

31. Remember our friends?
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32. Who are Bob’s Friends
SELECT p2.id, p2.name
FROM person p1
JOIN person_relationship rel
ON p1.id = rel.start_person_id
AND p1.id = 1 --Bob
AND rel.relationship_type=1 --Friend
JOIN person p2
ON p2.id = rel.end_person_id
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MATCH (b:Person {name:'Bob'})-[:FRIEND]->(f:Person)
RETURN f.name

33. Who are the Friends of Bob’s Friends?
SELECT p3.id, p3.name
FROM person p1
JOIN person_relationship rel1
ON p1.id = rel1.start_person_id
AND p1.id = 1 --Bob
AND rel1.relationship_type = 1 --Friend
JOIN person p2
ON p2.id = rel1.end_person_id
JOIN person_relationship rel2
ON p2.id = rel2.start_person_id
AND rel2.relationship_type = 1 --Friend
JOIN person p3
ON p3.id = rel2.end_person_id
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MATCH (b:Person {name:'Bob'})-[:FRIEND]->(f:Person)-[:FRIEND]->(fof:Person)
RETURN DISTINCT fof.name
MATCH (b:Person {name:'Bob'})-[:FRIEND *2]->(fof:Person)
RETURN DISTINCT fof.name

34. Bob’s Friends’ Friends’ Friends to the N
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MATCH (b:Person {name:'Bob'})-[:FRIEND *2]->(fof:Person)
RETURN DISTINCT fof.name
MATCH (b:Person {name:'Bob'})-[:FRIEND *]->(fof:Person)
RETURN DISTINCT fof.name
MATCH (b:Person {name:'Bob'})-[:FRIEND *..5]->(fof:Person)
RETURN DISTINCT fof.name
MATCH (b:Person {name:'Bob'})-[:FRIEND *2..5]->(fof:Person)
RETURN DISTINCT fof.name

35. What is Bob’s Bacon # ?
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MATCH path=shortestPath(
(kb:Person {name:'Kevin Bacon'})-[*]-(b:Person {name:'Bob'})
)
RETURN length(path)

36. Resources
- Developer Website
- https://neo4j.com/developer/
- Neo4J Docs
- https://neo4j.com/docs/
- Cypher Refcard
- https://neo4j.com/docs/cypher-refcard/
- Neo4J Book (free)
- Me @tbrantb on twitter
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