This package is abandoned and no longer maintained. No replacement package was suggested.

Answers Ask queries against a collection of Wikibase entities

0.3.1 2014-08-25 13:10 UTC

This package is not auto-updated.

Last update: 2020-01-22 01:41:39 UTC


WMDE has stopped development of this component. A fork with further development work done on it can be found at jeroen/query-engine.

Wikibase QueryEngine

Build Status Code Coverage Scrutinizer Code Quality Dependency Status

On Packagist: Latest Stable Version Download count

Wikibase QueryEngine is a component that supports running Ask queries against a collection of Wikibase entities.

It is primarily used by the Wikibase MediaWiki extensions, though has no dependencies whatsoever on these or on MediaWiki itself.

Recent changes can be found in the release notes.


You can use Composer to download and install this package as well as its dependencies. Alternatively you can simply clone the git repository and take care of loading yourself.


To add this package as a local, per-project dependency to your project, simply add a dependency on wikibase/query-engine to your project's composer.json file. Here is a minimal example of a composer.json file that just defines a dependency on Wikibase QueryEngine 1.0:

        "require": {
            "wikibase/query-engine": "1.0.*"


Get the Wikibase QueryEngine code, either via git, or some other means. Also get all dependencies. You can find a list of the dependencies in the "require" section of the composer.json file. Load all dependencies and the load the Wikibase QueryEngine library by including its entry point: WikibaseQueryEngine.php.


This library comes with a set up PHPUnit tests that cover all non-trivial code. You can run these tests using the PHPUnit configuration file found in the root directory. The tests can also be run via TravisCI, as a TravisCI configuration file is also provided in the root directory.

Running the tests



The public interfaces in this component are everything directly in the Wikibase\QueryEngine. Other classes and interfaces are typically package private, and should not be used or known about outside of the package. Each store implementation has its own list of additional public classes.


Public classes of the SQLStore:

Needed for construction:

  • SQLStore\SQLStore
    • SQLStore\StoreSchema
      • SQLStore\DataValueHandlers
    • SQLStore\StoreConfig

Needed for extension:

  • SQLStore\DataValueHandler

Constructing an SQLStore:

use Wikibase\QueryEngine\SQLStore\SQLStore;
use Wikibase\QueryEngine\SQLStore\StoreSchema;
use Wikibase\QueryEngine\SQLStore\StoreConfig;
use Wikibase\QueryEngine\SQLStore\DataValueHandlers;
use Wikibase\QueryEngine\SQLStore\DVHandler\NumberHandler;

$dvHandlers = new DataValueHandlers();

$dvHandlers->addMainSnakHandler( 'number', new NumberHandler() );

$store = new Store(
    new StoreSchema( 'table_prefix_', $dvHandlers ),
    new StoreConfig( 'store name' )


To get a list of available CLI commands, execute this in the root directory:

php queryengine

SQLStore internal structure

Table: entities

  • id, string: serialization of the entities id
  • type, string: type of the entity

Snak tables

All snak tables have the following fields:

  • row_id, int
  • subject_id, string
  • subject_type, string
  • property_id, string
  • statement_rank, int

The schema definition is dynamically build in StoreSchema.php.

Value snak tables

There is a value snak table per type of data value the store is configured to support.

All data value tables have a set of additional fields that are specific to the type of data value they store. For the types of data value natively supported by the store.

Valueless snak tables

Additional fields:

  • snak_type, int: type of the snak, ie "no value"


Wikibase QueryEngine has been written by the Wikidata team for the Wikidata project.


Related projects

Bugs on Phabricator