Neo4jrb

Neo4j.rb The Benefits of Graph Database Andreas Ronge

Who am I ?

NoSQL The problem with SQL: not designed for
Accelerating growth of data
Huge clustered environments
Complex and evolving data models
Choose the right tools - N ot O nly SQL

The CAP Theorem Can't achieve all three, pick two
C onsistency – all readers will see the same write
A vailability – tolerant of node failures
P artition tolerant – if lost interconnect between nodes
Many NoSQL databases choose
Sacrifice consistency over availability
Eventual consistency instead of ACID (but not Neo4j)

What is Neo4j.rb ? Neo4j
A Graph Database written in Java
Accessible from a Java API, but also
HTTP/REST interface
Language binding - Python, Ruby, Scala, Groovy
Gremlin ./outE[@label='created']/inV/inE[@label='created']/outV[g:except($_)]
Neo4j.rb
A language binding for (J) Ruby

A Ruby Crash Course

What is a Graph Database ?

Graph DB vs. SQL id name 1 andreas 2 peter id p1_id p2_id since 1234 1 2 2002 People Friends friend since: 2002 name: andreas name: peter

Graph DB vs SQL

Benefit 1 Domain Modeling

Benefit 2 No O/R mismatch

Benefit 3 Semi-structured information

Benefit 4 No Schema

DEMO TIME Does Thomas Andersson know someone [who knows]* called Agent Smith ? Benefit 5 Deep traversals

Neo4j(.rb) Features Neo4j
Embedded
ACID Transactions
Lucene Integration
Graph Algorithms
Neo4j.rb
Object Oriented Mapping
“Drop in” replacement for Rails Active Model
Improved/extended API (lucene, rules, migrations,...)

Embedded Easier to install, deploy & test Is running in same thread as your application No network connection to DB needed No Database Tier

Another Ruby Crash Course Ruby Java

Transactions ACID
a tomicity, c onsistency, i solation, d urability
only write locks, no read locks

Object Oriented Mapping Neo4j and a Dynamic Language – A Perfect Match ! Ruby Class A Neo4j Node _class: Person name: andreas

How do I find things ?
Start from Reference Node
Graph as an Index
Use Lucene

Reference Node Find Thomas Andersson Neo4j.ref_node.outgoing(:root).first REF_NODE Thomas Andersson

Use the Graph as an Index A A B Neo4j.ref_node.outgoing('A').each {...} RefNode name andreas name anders name bertil

Lucene Full-featured text search engine Features
Phrase queries, wildcard queries, proximity queries, range queries and more
Ranked searching
Sorting
Date-range
Sorting by any field

Lucene in Neo4j.rb

NodeMixin Lucene Integration Declared properties DSL for relationship traversal Migrations Lists Cascade Delete Works with inheritance

Ruby Class Mapping: Relationships friend friend name andreas name peter name david

Incoming Relationship Same relationship different direction Same _class = Actor name = 'keanu' _class = Movie name = 'matrix'

Ruby on Rails/Active Record “drop in” replacement

A Common Problem I have a
System already in production
Huge database
I need to
Change the structure of the database
Solution:
Migrations

Migrations: Direct

Migrations: Lazy (Neo4j::LazyMigrationMixin)

Inheritance

Recommendation Engine Likes Likes Likes Recommend This 1 2 4 3 5 Bertil Caesar Adam

Example, Recommendation likes other_people 4 2 5 3 1

Included Graph Algorithms Shortest paths, Simple paths, Graph measures ... node1 node2

High Availability Online Backup - hot spare Read-slave replication Write master election

Neo4j – An Object DB ? Neo4j has very fast traversals
Avoids loading properties
No need to declare two way relationships
A relationship has a start and end node
Does have two ways of finding objects
Traversals
Lucene
Optimized for Graph Algorithms

Conclusions: Benefits Express your domain as a Graph
Domain Modeling
No O/R mismatch
Efficient storage of Semi Structured Information
Schema Less
Express Queries as Traversals
Fast deep traversal instead of slow SQL queries that span many table joins

When NOT use Graph DB Don't have a graph related problem ? Not too much changing requirements ? Easy to organized data into:
Tables, Documents or Key-Value models ?
Few & well defined relationships in the domain ? Don't have SQL queries that span many table joins ? Many YES => maybe Graph DB not a good choice

When should I use a Graph DB ? Need to solve a graph related problem ?
Recommendations, Shortest path, Social Networks
Have a complex and evolving data model ? Few mandatory and many optional attributes ? Big part of domain is expressed as relationships ? Have SQL queries that span many table joins ? Many YES => maybe a Graph DB is a good choice

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Neo4jrb

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