From: Brad Jorsch <bjorsch@wikimedia.org>
Date: Thu, 23 May 2019 16:58:19 +0000 (-0400)
Subject: API: Add IGNORE INDEX to avoid bad plan in ApiQueryRevisions
X-Git-Tag: 1.34.0-rc.0~1593^2
X-Git-Url: http://git.cyclocoop.org/%22.%20generer_url_ecrire%28%22sites_tous%22%2C%22%22%29.%20%22?a=commitdiff_plain;h=a3f0784b18c27f84399cafe501b71015c87076be;p=lhc%2Fweb%2Fwiklou.git

API: Add IGNORE INDEX to avoid bad plan in ApiQueryRevisions

None of the queries generated by ApiQueryRevisions should be using the
`rev_timestamp` index, but MariaDB is insisting on doing so for one
particular query anyway.

Bug: T224017
Change-Id: I9476532d5896d9ba901c4c7398890bfecb1a318d
---

diff --git a/includes/api/ApiQueryRevisions.php b/includes/api/ApiQueryRevisions.php
index e60835bb02..ee6a264281 100644
--- a/includes/api/ApiQueryRevisions.php
+++ b/includes/api/ApiQueryRevisions.php
@@ -389,6 +389,10 @@ class ApiQueryRevisions extends ApiQueryRevisionsBase {
 
 		$this->addOption( 'LIMIT', $this->limit + 1 );
 
+		// T224017: `rev_timestamp` is never the correct index to use for this module, but
+		// MariaDB (10.1.37-39) sometimes insists on trying to use it anyway. Tell it not to.
+		$this->addOption( 'IGNORE INDEX', [ 'revision' => 'rev_timestamp' ] );
+
 		$count = 0;
 		$generated = [];
 		$hookData = [];