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My Contributions - Critical flood of slow queries that is causing a DB overload on en-wiki
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Description

A flood of slow queries from ArticleFeedbackv5Hooks::contributionsData() caused AFT5 to overloaded db12. As a result, it is now disabled in its entirety on the English-language Wikipedia.

It looks like there is no af_user_id or af_user_ip index, so the query scans the whole aft_article_feedback table (200k rows) on every view of Special:Contributions, according to Tim Starling.

Needless to say, this is the most important bug we need to fix at this time, either by disabling feedback on MyContribs entirely, or by solving the specific problem about af_user_id and testing thoroughly that it solves the larger issue before deploying it in our next window.


Version: unspecified
Severity: blocker

Details

Reference
bz38813

Event Timeline

bzimport raised the priority of this task from to Unbreak Now!.Nov 22 2014, 1:10 AM
bzimport added a project: ArticleFeedbackv5.
bzimport set Reference to bz38813.

Ok so:

  • fix the issue by adding the appropriate index:

https://gerrit.wikimedia.org/r/#/c/16966/
Note: to be approved by Asher

  • undo Tim's disabling AFT, thus enabling AFT again:

https://gerrit.wikimedia.org/r/#/c/16967/