All the revision IDs of a page should be stored in log_search when that page is deleted. That way, if the page is undeleted, there is still a way to find out what page ID its revisions had at the time of deletion. This is useful for countering the merge page histories attack; see bug 69047.
Version: 1.24rc
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=69871