Leveraging the Power of Graph Databases in PHP

Leveraging the Power of Graph Databases

in PHP

Jeremy Kendall Atlanta PHP April 2015

Obligatory Intro Slide

Also - New Father

What Kind of Database?

Graphs != Charts

https://www.flickr.com/photos/markgroves/3065192499/

Graphs != Charts

http://stephenwildish.tumblr.com/post/101408321763/friday-project-witch-moral-compass

Graph Databases• Data Model

• Nodes with properties

• Typed relationships

• Strengths

• Highly connected data

• ACID

• Weaknesses

• Paradigm shift

• Examples

• Neo4j, Titan, OrientDB

Why Care?• All the NoSQL Joy

• Schema-less

• Semi-structured data

• Escape from JOIN Hell

• Speed

Why Care?

• Relationships have 1st class status

• Just as important as the objects they connect

• You can have properties & labels

• Multiple relationships

Why Care?

Depth MySQL Query Time Neo4j Query Time Records Returned

2 0.028 (28 MS) 0.04 ~900

3 0.213 0.06 ~999

4 10.273 0.07 ~999

5 92.613 0.07 ~999

1,000 people with an average 50 friends each

Crazy SpeedDepth MySQL Query Time Neo4j Query Time Records Returned

2 0.016 (16 MS) 0.01 ~2500

3 30.27 0.168 ~125,000

4 1543.505 1.359 ~600,000

5 Stopped after 1 hour 2.132 ~800,000

1,000,000 people with an average 50 friends each

Neo4j + Cypher

Cypher

• Neo4j’s declarative query language

• Easy to pick up

• Some clauses and concepts familiar from SQL

Simple Example

Create Some NodesCREATE (jk:Person { name: "Jeremy Kendall" })CREATE (gs:Company { name: "Graph Story" })

CREATE (tn:State { name: "Tennessee" })CREATE (memphis:City { name: "Memphis" })CREATE (nashville:City { name: "Nashville" })

CREATE (hotchicken:Food { name: "Hot Chicken" })CREATE (bbq:Food { name: "Barbecue" })CREATE (photography:Hobby { name: "Photography" })CREATE (language:Language { name: "PHP" })

// . . . snip . . .

Create Some Relationships

// . . . snip . . .

CREATE (jk)-[:WORKS_AT { title: {"CTO"}]->(gs), (jk)-[:LIVES_IN]->(memphis)-[:LIVED_IN]->(nashville), (hotchicken)-[:ONLY_IN]->(nashville), (bbq)-[:ONLY_IN]->(memphis), (jk)-[:LOVES]->(hotchicken), // . . . snip . . .

// . . . snip . . .

Example Cypher Query

MATCH (p:Person { name: "Jeremy Kendall" })-[:LOVES]->(l)WITH p, lMATCH (p)-[:WORKS_AT]->(j)WITH p, l, jMATCH (p)-[:LIVES_IN]->(c:City)-[:LIVED_IN*0..]->(o:City)RETURN p, l, j, o

Query Result

However!

Easy to Model, Challenging to Master

Subtle(-ish) Bug

Neo4j + PHP

Neo4jPHP• PHP wrapper for the Neo4j REST API

• Installable via Composer

• Used internally at Graph Story

• Used in this presentation

• Well tested

• https://packagist.org/packages/everyman/neo4jphp

Also see: NeoClient• Written by Neoxygen

• Alternative PHP wrapper for the Neo4j REST API

• Installable via Composer

• Accepted for internal use at Graph Story

• Well tested

• https://packagist.org/packages/neoxygen/neoclient

Connecting$neo4jClient = new \Everyman\Neo4j\Client( ‘yourgraph.example.com’, 7473);

$neo4jClient->getTransport() ->setAuth('username', 'password') ->getTransport()->useHttps();

Creating a Node and Label

$node = new Node($neo4jClient);

$label = $neo4jClient->makeLabel('Person');

$node->setProperty('name', ‘Jeremy Kendall');

$node->save()->addLabels(array($label));

Searching

// Searching for a label by property$label = $neo4jClient->makeLabel('Person');$nodes = $label->getNodes('name', $name);

Querying (Cypher)

$queryString = 'MATCH (p:Person { name: { name }}) RETURN p';

$query = new \Everyman\Neo4j\Cypher\Query( $neo4jClient, $queryString, ['name' => ‘Jeremy Kendall']);

$result = $query->getResultSet();

Named Parameters

Content Modeling: News Feeds

Graph Kit for PHP https://github.com/GraphStory/graph-kit-php

News Feed

• Modeled as a list of posts

• Newest post first

• All subsequent posts follow

• Relationships: LASTPOST and NEXTPOST

LASTPOST

Adding Contentpublic static function add($username, Content $content){ $queryString =<<<CYPHERMATCH (user { username: {u}})OPTIONAL MATCH (user)-[r:LASTPOST]->(lastpost)DELETE rCREATE (user)-[:LASTPOST]->(p:Content { title:{title}, url:{url}, tagstr:{tagstr}, timestamp:{timestamp}, contentId:{contentId} })WITH p, collect(lastpost) as lastpostsFOREACH (x IN lastposts | CREATE p-[:NEXTPOST]->x)RETURN p, {u} as username, true as ownerCYPHER;

$query = new Query( Neo4jClient::client(), $queryString, array( 'u' => $username, 'title' => $content->title, 'url' => $content->url, 'tagstr' => $content->tagstr, 'timestamp' => time(), 'contentId' => uniqid() ) ); $result = $query->getResultSet();

return self::returnMappedContent($result);}

Adding Content

MATCH (user { username: {u}})OPTIONAL MATCH (user)-[r:LASTPOST]->(lastpost)DELETE rCREATE (user)-[:LASTPOST]->(p:Content { title:{title}, url:{url}, tagstr:{tagstr}, timestamp:{timestamp}, contentId:{contentId} })WITH p, collect(lastpost) as lastpostsFOREACH (x IN lastposts | CREATE p-[:NEXTPOST]->x)RETURN p, {u} as username, true as owner

Adding Content

Adding Content$query = new Query( $neo4jClient, $queryString, array( 'u' => $username, 'title' => $content->title, 'url' => $content->url, 'tagstr' => $content->tagstr, 'timestamp' => time(), 'contentId' => uniqid() ));

Retrieving Contentpublic static function getContent($username, $skip){ $queryString = <<<CYPHERMATCH (u:User { username: { u }})-[:FOLLOWS*0..1]->fWITH DISTINCT f, uMATCH f-[:LASTPOST]-lp-[:NEXTPOST*0..]-pRETURN p, f.username as username, f = u as ownerORDER BY p.timestamp desc SKIP { skip } LIMIT 4CYPHER;

$query = new Query( Neo4jClient::client(), $queryString, array( 'u' => $username, 'skip' => $skip, ) );

Retrieving Content

MATCH (u:User { username: { u }})-[:FOLLOWS*0..1]->fWITH DISTINCT f, uMATCH f-[:LASTPOST]-lp-[:NEXTPOST*0..]-pRETURN p, f.username as username, f = u as ownerORDER BY p.timestamp desc SKIP { skip } LIMIT 4

Retrieving Content

Editing Contentpublic static function edit(Content $content){ $updatedAt = time();

$node = $content->node; $node->setProperty('title', $content->title); $node->setProperty('url', $content->url); $node->setProperty('tagstr', $content->tagstr); $node->setProperty('updated', $updatedAt); $node->save();

$content->updated = $updatedAt;

return $content;}

Deleting Contentpublic static function delete($username, $contentId){ $queryString = self::getDeleteQueryString( $username, $contentId );

$params = array( 'username' => $username, 'contentId' => $contentId, );

$query = new Query( $neo4jClient, $queryString, $params ); $query->getResultSet();}

Deleting Content: Leaf

// If leafMATCH (u:User { username: { username }})-[:LASTPOST|NEXTPOST*0..]->(c:Content { contentId: { contentId }})WITH cMATCH (c)-[r]-()DELETE c, r

Deleting Content: LASTPOST

// If lastMATCH (u:User { username: { username }})-[lp:LASTPOST]->(del:Content { contentId: { contentId }})-[np:NEXTPOST]->(nextPost)CREATE UNIQUE (u)-[:LASTPOST]->(nextPost)DELETE lp, del, np

Deleting Content: Other

// All otherMATCH (u:User { username: { username }})-[:LASTPOST|NEXTPOST*0..]->(before), (before)-[delBefore]->(del:Content { contentId: { contentId }})-[delAfter]->(after)CREATE UNIQUE (before)-[:NEXTPOST]->(after)DELETE del, delBefore, delAfter

Questions?

Thanks!

[email protected] @JeremyKendall

http://www.graphstory.com

Leveraging the Power of Graph Databases in PHP

Technology

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