CDB

CDB, short for "constant database", refers to a very fast and highly reliable database system which uses a simple file with key value pairs. In MediaWiki 1.16 (r52203), a PHP port of CDB was added. Starting with MediaWiki 1.25, it was split out into a separate library which can be used independently of MediaWiki.

Installing

To use it inside your application, simply run composer require wikimedia/cdb, or add a dependency in your composer.json. The current stable version is 1.0.1.

If you prefer using git, that's also an option: git clone https://gerrit.wikimedia.org/r/p/cdb.git, and autoload the library however you wish to.

If you wish to develop and contribute on the library, see developer access for gaining access to our code review system.

Usage

// Reading a CDB file
$cdb = \Cdb\Reader::open( 'db.cdb' );
$foo = $cdb->get( 'somekey' );

// Writing to a CDB file
$cdb = \Cdb\Writer::open( 'anotherdb.cdb' );
$cdb->set( 'somekey', $foo );

For actual usage examples, you can look at the following uses within MediaWiki:

• the interwiki cache
• the localisation cache
• Extension:Babel
• Extension:TrustedXFF
• Wikimedia's hetdeploy/multiversion

See also

• Memcached
• PHP configuration
• http://laxstrom.name/blag/?s=cdb
• http://cr.yp.to/cdb.html
• https://packagist.org/packages/wikimedia/cdb