API: More avoiding MySQL filesorts in list=allpages

For some reason, slaves but not masters are filesorting on the query
here. So add another special case for MySQL to vary the query in a
manner that makes both happy.

Bug: T78276
Change-Id: I4d0c48e7c28f6a6b2e8c317275d15301bf158f03

diff --git a/includes/api/ApiQueryAllPages.php b/includes/api/ApiQueryAllPages.php
index 0149ad2..e441991 100644 (file)
--- a/includes/api/ApiQueryAllPages.php
+++ b/includes/api/ApiQueryAllPages.php
@@ -175,10 +175,14 @@ class ApiQueryAllPages extends ApiQueryGeneratorBase {
                        // 1999 rules works fine, but that breaks other DBs. Sigh.
                        /// @todo Once we drop support for 1992-rule DBs, we can simplify this.
                        $dbType = $db->getType();
-                       if ( $dbType === 'mysql' || $dbType === 'sqlite' ||
-                               $dbType === 'postgres' && $db->getServerVersion() >= 9.1
-                       ) {
-                               // 1999 rules, or screw-the-rules
+                       if ( $dbType === 'mysql' || $dbType === 'sqlite' ) {
+                               // Ignore the rules, or 1999 rules if you count unique keys
+                               // over non-NULL columns as satisfying the requirement for
+                               // "functional dependency" and don't require including
+                               // constant-in-WHERE columns in the GROUP BY.
+                               $this->addOption( 'GROUP BY', array( 'page_title' ) );
+                       } elseif ( $dbType === 'postgres' && $db->getServerVersion() >= 9.1 ) {
+                               // 1999 rules only counting primary keys
                                $this->addOption( 'GROUP BY', array( 'page_title', 'page_id' ) );
                        } else {
                                // 1992 rules