Presentation of Neo4j based on my experience through the book 7 databases in 7 weeks.

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7 databases in 7 weeks
Neo4j – 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?

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Neo4j loves whiteboards

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Node = Vertex
Relationship = Edge
Property = Attribute
BTW, what is a graph?
Nexus 4
manufacturer: ‘LG’
color: ‘Black’
Nicolas
traits:
{‘nice’,
‘awesome’}
Loves
how_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 DSL
g.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 Java
but 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 API
Paths algorithms: shortest, all paths, Dijkstraaaahhh (500)
Index: manual indexing
Full-Text search
Cypher
Movie database exercice
using external Graph algorithms
Day-2 – Let’s move to the REST API!

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1 server: ACID
One-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 cost
6,000 USD/node/year for Commercial
24,000 USD/node/year for Enterprise (HA)
Index support??

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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