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Tél : +33 (0)1 58 56 10 00Fax : +33 (0)1 58 56 10 01www.octo.com© OCTO 2012

50, avenue des Champs-Elysées75008 Paris - FRANCE

7 databases in 7 weeksNeo4j – A graph database presentation

Nicolas Landier

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Neo4j, WTF?

BTW, what is a graph?

Day-1: WebUI

Day-2: REST API

Day-3: Consistency and HA

Demo?!

Strengths & Weaknesses

Outline

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Graph oriented database

Key-Value minded

Schemaless

Graph theory based

Whiteboard friendly…

Neo4j, WTF?

NoSQL

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Neo4j loves whiteboards

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Node = Vertex

Relationship = Edge

Property = Attribute

BTW, what is a graph?

Nexus 4manufacturer: ‘LG’color: ‘Black’

Nicolastraits: {‘nice’, ‘awesome’}

Loveshow_much: ‘you don’t want to know’

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Great and useful WebUI to get familiar and test

Create a first data model

Gremlin: a Groovy based syntax => exploratory queries

Cypher: a SQL-like syntax => criteria queries

Create your own DSLg.V.filter{it.name=='Prancing Wolf Ice Wine 2007'}.varietal.name

Day-1 – Head first in the web UI!

###CRASH!! $$DB files fucked up### PLEASE FORMAT###

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You can Neo4j query from Javabut you better stick with Cypher if you do so!

ice_wine = g.v(0)

ice_wine.out('grape_type').in('grape_type').filter{ !it.equals(ice_wine) }

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REST APIPaths algorithms: shortest, all paths, Dijkstraaaahhh (500)

Index: manual indexing

Full-Text search

Cypher

Movie database exerciceusing external Graph algorithms

Day-2 – Let’s move to the REST API!

Eca!

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1 server: ACIDOne-liners are implicitly transactions (like PostgreSQL)

Transactions can be handled manually

Cluster: no more ACID (enterprise only)Master gets elected by servers

R/W can be handled by every server but the Master is GOLD version of data

Replication is strictly handled by the Master

Eventual consistency

Zookeeper-based

Day-3 – Let’s be HA!

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To relax your eyes

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Write transactions can be performed on any database instance in a cluster.

Neo4j HA is fault tolerant and can continue to operate from any number of machines down to a single machine.

Slaves will be automatically synchronized with the master on write operations.

If the master fails a new master will be elected automatically.

The cluster automatically handles instances becoming unavailable (for example due to network issues), and also makes sure to accept them as members in the cluster when they are available again.

Transactions are atomic, consistent and durable but eventually propagated out to other slaves.

Updates to slaves are eventual consistent by nature but can be configured to be pushed optimistically from master during commit.

If the master goes down any running write transaction will be rolled back and new transactions will block or fail until a new master has become available.

Reads are highly available and the ability to handle read load scales with more database instances in the cluster.

Neo4J HA summed up

Source: http://docs.neo4j.org/chunked/snapshot/ha-how.html

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Demo

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Strengths & Weaknesses

2 languages:Groovy support (Gremlin)

Cypher

Simple data model: « JIT » for developers

« Promised scalability »

Great for human-related network data

DSL definitions are written in stone (not editable, not updatable)

Licence cost6,000 USD/node/year for Commercial

24,000 USD/node/year for Enterprise (HA)

Index support??

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NEO4J IS BEAUTIFUL!

BUT BE CAREFUL.

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Information is based on my experience from the book from 7 Databases in 7 weeks authored by Eric Redmond and Jim R. Wilson.

Thanks for their work.

Source