Template:DBwarning/en

Do not change $wgDBmwschema after Setup.php has been included. Note: Setup.php initializes various paths, includes some common files, starts sessions, and performs various other setup tasks for a request. It is not related to the installation or setup of MediaWiki.
Only files in includes/db/ should use $wgDBmwschema, while everything else should use the dbSchema() method provided by the Wikimedia\Rdbms\IDatabase interface or extract it from the getDomainId() method in either the Wikimedia\Rdbms\ILoadBalancer or the Wikimedia\Rdbms\ILBFactory interface. The DatabaseDomain class can extract such components from a database domain ID.
If you configure $wgDBservers or $wgLBFactoryConf, you still need to define $wgDBname, $wgDBmwschema (if applicable for the DB type), and $wgDBprefix (if applicable for the DB type). The combination of $wgDBname, $wgDBmwschema, and $wgDBprefix define the current wiki's database domain. This is also called the local database domain. The 'dbname' and 'tablePrefix' settings in $wgDBservers and $wgLBFactoryConf only define the default DB/prefix when a connection is requested with DatabaseDomain::newUnspecified()->getId() (the empty string) as the database domain, e.g. wfGetDB( DB_REPLICA, [], '' ). Note that functions calls like wfGetDB( DB_REPLICA ), which simply omit the database domain, are assumed to refer to the local database domain.