Page deletion occurs when a page is deleted by the
action=delete parameter to index.php or by API:Delete.
With both of these methods, the option exists to also delete the associated talk page (if one exists).
All of the revisions in the page are moved from the revision table to the archive table and the page entry is deleted.
The page deletion system is entirely separate from the revision deletion system.
It changes the value of revision.rev_deleted while leaving the affected row(s) in the revision table and leaving the page table unchanged.