Hi all,

I have a query that used to do a GROUP BY on rev_user and now I have migrated it to do so using rev_actor instead. The latest version looks like this and its performance is not good at all. In fact, I left it running for fawiki for several hours and it did not generate any results (it used to generate results in about 30-40 minutes). Also, the execution plan that is shown in the second link involves some tables like filearchive, image and oldimage that are not part of the query.

Is this a side effect of the revision_actor_temp table?

Also, what is that "key0" about, which is not associated with any tables?

Finally, any advice on how to make it more efficient is highly appreciated.

Thanks!

Huji