Last modified: 2014-05-03 01:08:23 UTC
[[Special:Random/Education Program]] gives this: ---- A database query error has occurred. This may indicate a bug in the software. Function: RandomPage::selectRandomPageFromDB Error: 0 ---- Not sure if this is a bug in the EducationProgram extension or in MediaWiki core code.
The following lines show up in dberrors.log when I try loading that page: Wed Dec 11 14:12:41 UTC 2013 mw1112 enwiki Connection lost and reconnected after 99.509s, query: SELECT /* RandomPage::selectRandomPageFromDB */ page_title,page_namespace FROM `page` FORCE INDEX (page_random) WHERE page_namespace = '446' AND page_is_redirect = '0' AND (page_random >= 0) ORDER BY page_random LIMIT 1 Wed Dec 11 14:12:41 UTC 2013 mw1112 enwiki RandomPage::selectRandomPageFromDB 10.64.32.22 0 SELECT page_title,page_namespace FROM `page` FORCE INDEX (page_random) WHERE page_namespace = '446' AND page_is_redirect = '0' AND (page_random >= 0) ORDER BY page_random LIMIT 1 A quick check in the database finds zero rows for SELECT * FROM page WHERE page_namespace = '446' on enwiki.
Hmm, the FORCE INDEX looks inappropriate there.
Rage Soss: ping?
I talked with Andrew Green about this a little bit yesterday. From a user perspective, it's not very important to have Special:Random work for the Education Program namespace, but I suggested to Andrew to simply catch this situation and display a message to the effect that Special:Random is not available for that namespace.
It looks like there are two issues here: 1. Special:Random doesn't handle empty namespaces (or almost-empty namespaces, I'd guess) well when there are a very large number of pages in other namespaces. 2. EducationProgram doesn't work with Special:Random (or Special:AllPages, or probably various other bits of MediaWiki), because it doesn't use the page table at all. I'd suggest splitting the second problem to a new bug.
Spotted this in bug 57285 via slow query logs. Same conclusion: the forced index is no longer appropriate.
Error is now impossible, because a message is shown: Random article There are no pages in the following namespace: Education_Program.
