Intro to Neo4j

@praveenasekhar / @markneedham

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Welcome!

Logistics

‣ Wi-fi• network: LNVisitor• user/password: LNGuest / LNGuest

‣ Grab a USB key from one of the tables or download from neo4j.com/download

‣ Install Neo4j 3.0.3

They GoT the title wrong ...

There maybe spoilers.. [Maybe]

Example

Game of Thrones Wiki

By the end you will help us work out

‣ Who is the most prominent character in a season?

‣ Which house features the most characters? ‣ How are Starks and Targaryens related?

A quick show of hands...

How many people have used databases before?

A quick show of hands...

How many people have used Neo4j before?

A quick show of hands...

How many people have watched Game of Thrones?

Whiteboard / Post-It Exercise

Everyone!

List down different types of entities and relationships that tie them in the Game of Thrones universe!

http://gameofthrones.wikia.com/wiki/Game_of_Thrones_Wiki

‣ Actors‣ Characters‣ Allegiances‣ Houses‣ Episodes‣ Locations

What data do we have?

‣ An introduction to Neo4j and the Cypher query language

‣ GoT characters and episodes‣ GoT houses ‣ GoT family relationships

Agenda

Example

A brief into to the graph data model

GoT graph model

Nodes

Labels

Properties

Relationships

Introducing Cypher

What is Cypher?

‣ The graph query language

‣ Declarative and based on finding patterns

‣ ASCII Art + Query Language = Cypher

Nodes

() or (n)

● Surrounded with parentheses

● Use an alias to refer to our node later

(n:Label)● Specify a Label - grouping nodes by roles or types

● Think of Labels like "Tables"++

(n:Label {prop: 'value'})● Nodes can have properties

Relationships

--> or -[:TYPE]->

● Hyphenated & encased in square brackets● Like labels, a relationship type starts with a colon :● < > Specify the direction of the relationship

-[:TYPE {propertyName: "value"}]->

● Relationships can have properties too!

Our first graph

‣ Navigate to http://localhost:7474 ‣ Type the following into the pane at the top::play http://guides.neo4j.com/got

Follow AlongRun the first guide with us

When there are slides to see

ContinueContinue with the Guide

Take NoteConstraints

Unique constraints

We create unique constraints to:

‣ ensure uniqueness ‣ allow fast lookup of nodes which match

these (label,property) pairs.

Unique constraints

We create unique constraints to:

‣ ensure uniqueness ‣ allow fast lookup of nodes which match

these (label,property) pairs.CREATE CONSTRAINT ON (c:Character)

ASSERT c.name IS UNIQUE

ContinueContinue with the Guide

End of Section 1Continue with the Guide

Follow AlongRun the next guide with us

Take NoteDeleting

Deleting data

The DELETE command allows us to delete nodes and relationships...but we can’t delete nodes if they still have relationships

Deleting data

The DELETE command allows us to delete nodes and relationships...but we can’t delete nodes if they still have relationshipsMATCH (n)

DELETE n

org.neo4j.kernel.api.exceptions.ConstraintViolationTransactionFailureException:

Cannot delete node<0>, because it still has relationships. To delete this node, you

must first delete its relationships.

Deleting data

The DETACH DELETE command is our friend when we want to delete a node and all relationships attached to it.MATCH (n)

DETACH DELETE n

Deleting schema

We can delete constraints as well by changing ‘CREATE’ to ‘DROP’ in the commandCREATE CONSTRAINT ON (c:Character)

ASSERT c.name IS UNIQUE;

DROP CONSTRAINT ON (c:Character)

ASSERT c.name IS UNIQUE;

Follow AlongContinue with the guide

Take NoteLOAD CSV

LOAD CSV

‣ Import data from a HTTP or file URI• LOAD CSV WITH HEADERS FROM "file://" AS row

LOAD CSV WITH HEADERS FROM "http://" AS row

‣ Transform and convert CSV values• MATCH (node1:Label {property: row.propertyValue})

CREATE (node2:Label {property: row.propertyValue})

MERGE (node3:Label {property: row.propertyValue})

• CREATE (node1)-[:REL_TYPE]->(node2)

MERGE (node1)-[:REL_TYPE]->(node2)

ContinueContinue with the Guide

Take NoteAggregation queries

Aggregation queries

We don’t specify a GROUP BY key when using aggregation functions. The key is all non aggregation fields in the RETURN statement.

Aggregation queries

We don’t specify a GROUP BY key when using aggregation functions. The key is all non aggregation fields in the RETURN statement.

MATCH (character:Character)-[:APPEARED_IN]->()

RETURN character.name, COUNT(*) AS appearances

ORDER BY appearances DESC

Follow AlongContinue with the guide

End of Section 2Let’s take a 5 minute break

Follow AlongOnto the next guide

Take NoteAdvanced aggregation queries

Let’s talk about joins

Houses Episodes

Characters

Houses Episodes

Characters

Let’s talk about joins

We can use the WITH clause to work around this problem

WITH

The WITH clause allows query parts to be chained together, piping the results from one to be used as starting points or criteria in the next.

WITH

It’s used to:

‣ limit the number of entries that are then passed on to other MATCH clauses.

‣ filter on aggregated values‣ separate reading from updating of the graph

WITH

MATCH (h:House)<-[:HAS_ALLEGIANCE_TO]-(c:Character)-[:APPEARED_IN]->()

RETURN c.id, c.name, COLLECT(h.name) AS houses, COUNT(*) AS appearances

ORDER BY appearances DESC

MATCH (h:House)<-[:HAS_ALLEGIANCE_TO]-(c:Character)

WITH c, COLLECT(h.name) as houses

MATCH (c)-[:APPEARED_IN]->()

RETURN c.id, c.name, houses, COUNT(*) AS appearances

ORDER BY appearances DESC

Follow AlongContinue with the guide

End of Section 3One more to go

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Thanks for coming!

That’s all for today!

Thanks for coming!

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ResourcesHBO Game of Thrones

Wikipedia

Family Tree House Stark

Game of Thones Wikia

Cool Interactive Infographic

http://www.fastcodesign.com/1671439/infographic-every-murder-in-game-of-thrones-in-just-90-seconds

https://www.washingtonpost.com/graphics/entertainment/game-of-thrones/

http://winteriscoming.net/2016/04/18/infographic-shows-that-death-has-been-good-for-game-of-thrones-ratings/

15 GoT Infographics

http://hauteslides.com/2011/05/game-of-thrones-infographic-illustrated-guide-to-houses-and-character-relationships/

Social Media Infographics

Betrayal Graph

Impressive GoT Railroad Map

Character Relationship Graph from Book 3 NLP Analytics