Manual:Hooks/DeleteUnknownPreferences

This hook is called by the maintenance script to build a WHERE clause with which to delete preferences that are not known about. This hook is used by extensions that have dynamically-named preferences that should not be deleted in the usual cleanup process. For example, the Gadgets extension creates preferences prefixed with 'gadget-', and so anything with that prefix is excluded from the deletion.

Arguments

 * : An array that will be passed as the $cond parameter to IDatabase::select to determine what will be deleted from the user_properties table.
 * : The IDatabase object, useful for accessing $db->buildLike etc.

Example
To prevent the deletion of any preference whose name ends in :