Question

I want to use a graph database using php. Can you point out some resources on where to get started? Is there any example code / tutorial out there? Or are there any other methods of storing data that relate to each other in totally random/abstract situations?

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Very abstract example of the relations needed: John relates to Mary, both relate to School, John is Tall, Mary is Short, John has Blue Eyes, Mary has Green Eyes, query I want is which people are related to Short people that have Green Eyes and go to School -> answer John

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Another example:

    TrackA -> ArtistA
           -> ArtistB

           -> AlbumA -----> [ label ]
           -> AlbumB -----> [   A   ]

           -> TrackA:Remix
           -> Genre:House

           -> [ Album ] -----> [ label ]
   TrackB  -> [   C   ]        [   B   ]

Example queries:

Which Genre is TrackB closer to? answer: House - because it s related to Album C, which is related to TrackA and is related to Genre:House

Get all Genre:House related albums of Label A : result: AlbumA, AlbumB - because they both have TrackA which is related to Genre:House

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It is possible in MySQL but it would require a fixed set of attributes/columns for each item and a complex non-flexible query, instead I need every attribute to be an item by itself and instead of belonging to something, to be related to something.

Answer 1

There s some work going on to make the Neo4j graph database available from PHP, see this wiki page for more information! Regarding how to model your domain as a graph, the user mailing list tends to be pretty awesome.

Update: there s now a short getting started blog post for a PHP neo4j REST client.

Answer 2

Sounds to me a little bit like a "typical" Prolog problem... which is a quite different programming language than PHP. But perhaps you could work with popen.

Or you define an SQL table with columns [ id, predicate, atom1, atom2 ], to store the truthness of "Mary has Green Eyes": predicate = "has", atom1 = "Mary", atom2 = "Green Eyes".

Now you could join and filter the predicates and attributes with the SQL of your choice.

Answer 3

It looks like a semantic web problem. So you have to figure out how you can use PHP and the semantic web together. Maybe this link http://bnode.org/blog/2009/05/25/back-from-new-york-semantic-web-for-php-developers-trip can help?

Answer 4

It kind of sounds like you should approach it this way:

1) Code a graph object that will let you query your data the way you want.

2) Write a persistence layer for your object

3) optimize the calls that do your query s in the graph object to use database calls when appropriate (for example, if you need to conserve memory).

Answer 5

My suggestion is to pick a Java-based graph DB like OrientDB or neo4j and then use it via the PHP/Java bridge. In the near future neo4j (and at some point OrientDB as well) should get native php support and you can replace the bridge with native access.

Answer 6

well taking into account this question is one year old, it might still be interesting to note that you can do such a query with every rdf datastore that supports sparql or comparable languages.

Answer 7

Take also a look to this article about the usage of OrientDB with PHP: http://www.odino.org/346/orientdb-the-graph-db-for-the-web

Answer 8

You can also find a Rexster client for php : https://github.com/PommeVerte/rexpro-php

As extra information. Rexster can load graphs from various other graph dbs such as Neo4j and OrientDb among others.

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