Recently somebody dumped a huge amount of text into Template:POTD on enwiki, and people were unable to revert it as the edits failed (timing out and showing squid error pages).

As a temporary measure I cleared its outgoing pagelinks and reverted the page_latest manually to an earlier revision. However it remained uneditable.

I found that the edit updates were hanging while trying to touch the page_touched timestamp on the pages linking to the template. By changing it from a single multiple-target UPDATE statement to separate per-record UPDATEs I found that it was hanging on a particular record:

mysql> UPDATE `page` SET page_touched='20050711222253' WHERE page_id=2152287 limit 1;

Updating this record, referenced either by title or by id, just hangs for a couple minutes until it times out trying to get a lock. But there's no competing query that I can see, and no reason for an open lock.

I've got James poking at it, hopefully we can figure it out...

-- brion vibber (brion @ pobox.com)