Last modified: 2014-01-11 20:16:52 UTC
The following query is much slower on MariaDB enwiki with the FORCE INDEX than without it: SELECT /* IndexPager::buildQueryInfo (NewPagesPager) xxx.xxx.xxx.xxx */ rc_namespace, rc_title, rc_cur_id, rc_user, rc_user_text, rc_comment, rc_timestamp, rc_patrolled, rc_id, rc_deleted, page_len AS length, page_latest AS rev_id, rc_this_oldid, page_namespace, page_title, fp_stable, fp_pending_since, (SELECT GROUP_CONCAT(ct_tag SEPARATOR ', ') FROM `change_tag` WHERE ct_rc_id=rc_id ) AS ts_tags FROM `recentchanges` FORCE INDEX (new_name_timestamp) INNER JOIN `page` ON ((page_id=rc_cur_id)) LEFT JOIN `flaggedpages` ON ((fp_page_id = rc_cur_id)) WHERE rc_new = '1' AND (rc_namespace != '6') AND page_is_redirect = '0' ORDER BY rc_timestamp DESC LIMIT 51; With force: > 1min, ~500000 rows hit with a filesort. Without force: < 1ses, ~100 rows hit using rc_timestamp, no filesort.
Change 100537 had a related patch set uploaded by Springle: Remove problem forced index. Bug 58256. https://gerrit.wikimedia.org/r/100537
Change 100537 had a related patch set uploaded by Aaron Schulz: Remove problem forced index. Bug 58256. https://gerrit.wikimedia.org/r/100537
Change 100537 merged by jenkins-bot: Remove problem forced index https://gerrit.wikimedia.org/r/100537