Last modified: 2010-05-15 15:28:11 UTC
Seen on Ariel: jawiki 211 Query SELECT cur_namespace,cur_title FROM imagelinks,cur WHERE il_to='Stubico.png' AND il_from=cur_id 20,135 records returned by this query. A select count(*) on imagelinks for this il_to on a slave took under a second on Bacon, so getting the cur records is the slow part. Will be helped by a smaller cur record. By the time it had finished, Ariel had accumulated more than 500 queries outstanding. Adding it to querybane, which may block display of this image description page for ja. Requests/suggestions: 1. Switch this query to use database slaves. 2. If there is a limit on how many articles are displayed, add that to a limit statement in this query. 3. If no display limit yet, do SELECT count(*) FROM imagelinks WHERE il_to='Stubico.png' first, then have some suitable partial display when there are many records. Assuming this is an image description pagethis lets people get to an image description page without triggering a costly query. Maybe display full list on a linked page and only the first 50 or 100 on the main image description page. 3b When doing 3a, don't add an order by clause - you'll force retrieval of many more records to get the properly ordered subset. 3c. As temporary workaround, add limit 500 or limit 1000 to the query.
Have added temporary LIMIT 500. Paging etc would be better.
Thanks.
Rather than the select count, use limit 501 instead of 500, don't display result 501 and use the presence of 501 to tell you that there are more results. One less query to make.
Assume fixed in 1.5 - at least worked around.
