Manual:DeleteArchivedRevisions.php

Details
deleteArchivedRevisions.php file is a maint-scripts>Special:MyLanguage/Manual:Maintenance scripts|maintenance script to delete all the archived (hidden from public view) revisions, by clearing out the arcTable>Special:MyLanguage/Manual:Archive table|archive table. These revisions will no longer be restorable. The pages are permanently deleted.

When a page is 'deleted' by an administrator (sysopdel>Help:Sysop deleting and undeleting|Help:Sysop deleting and undeleting), records are moved from the 'revision' table to the 'archive' table, although the bulk of the data (page text) remains in the 'text' table. The script deletes all records from the archive table and then invokes  to purge the text records which no revision links to. This can be useful for reducedb>Special:MyLanguage/Manual:Reduce size of the database|reducing the size of the database but it does mean you lose the ability to restore the according revisions.

Prior to MediaWiki 1.16, a helper file  contained the class that performs the work. This class was merged into deleteArchivedRevisions.php in 1.16.