https://bugzilla.wikimedia.org/show_bug.cgi?id=58256
Web browser: ---
Bug ID: 58256
Summary: IndexPager::buildQueryInfo (NewPagesPager) query needs
tuning
Product: MediaWiki
Version: 1.23-git
Hardware: All
OS: All
Status: NEW
Severity: major
Priority: Unprioritized
Component: Database
Assignee: wikibugs-l@lists.wikimedia.org
Reporter: sprin...@wikimedia.org
Classification: Unclassified
Mobile Platform: ---
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.
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