From: Yuri Astrakhan <yurik@users.mediawiki.org>
Date: Sat, 11 Nov 2006 21:38:18 +0000 (+0000)
Subject: bugfix 6440: updated indexes to improve backlinking queries. May be very slow on... 
X-Git-Tag: 1.31.0-rc.0~55222
X-Git-Url: http://git.cyclocoop.org/%22.%24redirect_annul.%22?a=commitdiff_plain;h=4e6fbd33bc3cec6d7237aa269ff1e1b6623d4825;p=lhc%2Fweb%2Fwiklou.git

bugfix 6440: updated indexes to improve backlinking queries. May be very slow on large wikis.
---

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index 510f8254c3..d7f9316b18 100644
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -176,7 +176,7 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
 * Do a check for the PHP 5.0.x 64-bit bug, since this is much more disruptive
   as of MW 1.8 than it used to be. Install or upgrade now aborts with a
   warning and a request to upgrade.
-
+* (bug 6440) Updated indexes to improve backlinking queries (links, templates, images)
 
 == Languages updated ==
 
diff --git a/maintenance/archives/patch-backlinkindexes.sql b/maintenance/archives/patch-backlinkindexes.sql
new file mode 100644
index 0000000000..5facd9ea1b
--- /dev/null
+++ b/maintenance/archives/patch-backlinkindexes.sql
@@ -0,0 +1,19 @@
+-- 
+-- patch-backlinkindexes.sql
+-- 
+-- Per bug 6440 / http://bugzilla.wikimedia.org/show_bug.cgi?id=6440
+--
+-- Improve performance of the "what links here"-type queries
+-- 
+
+ALTER TABLE /*$wgDBprefix*/pagelinks
+   DROP INDEX pl_namespace,
+   ADD INDEX pl_namespace(pl_namespace, pl_title, pl_from);
+
+ALTER TABLE /*$wgDBprefix*/templatelinks
+   DROP INDEX tl_namespace,
+   ADD INDEX tl_namespace(tl_namespace, tl_title, tl_from);
+   
+ALTER TABLE /*$wgDBprefix*/imagelinks
+   DROP INDEX il_to,
+   ADD INDEX il_to(il_to, il_from);
diff --git a/maintenance/mysql5/tables.sql b/maintenance/mysql5/tables.sql
index 1e63b91d41..ed8c68465c 100644
--- a/maintenance/mysql5/tables.sql
+++ b/maintenance/mysql5/tables.sql
@@ -383,7 +383,7 @@ CREATE TABLE /*$wgDBprefix*/pagelinks (
   pl_title varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY pl_from (pl_from,pl_namespace,pl_title),
-  KEY (pl_namespace,pl_title)
+  KEY (pl_namespace,pl_title,pl_from)
 
 ) ENGINE=InnoDB, DEFAULT CHARSET=utf8;
 
@@ -403,7 +403,7 @@ CREATE TABLE /*$wgDBprefix*/templatelinks (
   tl_title varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY tl_from (tl_from,tl_namespace,tl_title),
-  KEY (tl_namespace,tl_title)
+  KEY (tl_namespace,tl_title,tl_from)
 
 ) ENGINE=InnoDB, DEFAULT CHARSET=utf8;
 
@@ -423,7 +423,7 @@ CREATE TABLE /*$wgDBprefix*/imagelinks (
   il_to varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY il_from (il_from,il_to),
-  KEY (il_to)
+  KEY (il_to,il_from)
 
 ) ENGINE=InnoDB, DEFAULT CHARSET=utf8;
 
diff --git a/maintenance/oracle/tables.sql b/maintenance/oracle/tables.sql
index 6733f95074..7b24d1ee08 100644
--- a/maintenance/oracle/tables.sql
+++ b/maintenance/oracle/tables.sql
@@ -109,14 +109,14 @@ CREATE TABLE pagelinks (
 	pl_title	VARCHAR2(255) NOT NULL
 );
 CREATE UNIQUE INDEX pl_from ON pagelinks(pl_from, pl_namespace, pl_title);
-CREATE INDEX pl_namespace ON pagelinks(pl_namespace, pl_title);
+CREATE INDEX pl_namespace ON pagelinks(pl_namespace, pl_title, pl_from);
 
 CREATE TABLE imagelinks (
 	il_from	 NUMBER(8) NOT NULL REFERENCES page(page_id) ON DELETE CASCADE,
 	il_to	 VARCHAR2(255) NOT NULL
 );
 CREATE UNIQUE INDEX il_from ON imagelinks(il_from, il_to);
-CREATE INDEX il_to ON imagelinks(il_to);
+CREATE INDEX il_to ON imagelinks(il_to, il_from);
 
 CREATE TABLE categorylinks (
   cl_from	NUMBER(8) NOT NULL REFERENCES page(page_id) ON DELETE CASCADE,
diff --git a/maintenance/tables.sql b/maintenance/tables.sql
index e68c9b072c..d210179657 100644
--- a/maintenance/tables.sql
+++ b/maintenance/tables.sql
@@ -371,7 +371,7 @@ CREATE TABLE /*$wgDBprefix*/pagelinks (
   pl_title varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY pl_from (pl_from,pl_namespace,pl_title),
-  KEY (pl_namespace,pl_title)
+  KEY (pl_namespace,pl_title,pl_from)
 
 ) TYPE=InnoDB;
 
@@ -391,7 +391,7 @@ CREATE TABLE /*$wgDBprefix*/templatelinks (
   tl_title varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY tl_from (tl_from,tl_namespace,tl_title),
-  KEY (tl_namespace,tl_title)
+  KEY (tl_namespace,tl_title,tl_from)
 
 ) TYPE=InnoDB;
 
@@ -410,7 +410,7 @@ CREATE TABLE /*$wgDBprefix*/imagelinks (
   il_to varchar(255) binary NOT NULL default '',
   
   UNIQUE KEY il_from (il_from,il_to),
-  KEY (il_to)
+  KEY (il_to,il_from)
 
 ) TYPE=InnoDB;
 
diff --git a/maintenance/updaters.inc b/maintenance/updaters.inc
index d7c41aced6..f319cb4dd9 100644
--- a/maintenance/updaters.inc
+++ b/maintenance/updaters.inc
@@ -795,6 +795,32 @@ function do_rc_indices_update() {
 	}
 }
 
+function index_has_field($table, $index, $field) {
+	global $wgDatabase;
+	echo( "Checking if $table index $index includes field $field...\n" );
+	$info = $wgDatabase->indexInfo( $table, $index, __METHOD__ );
+	if( $info ) {
+		foreach($info as $row) {
+			if($row->Column_name == $field) {
+				echo( "...index $index on table $table seems to be ok\n" );
+				return true;
+			}
+		}
+	}
+	echo( "...index $index on table $table has no field $field; adding\n" );
+	return false;
+}
+
+function do_backlinking_indices_update() {
+	echo( "Checking for backlinking indices...\n" );
+	if (!index_has_field('pagelinks', 'pl_namespace', 'pl_from') ||
+		!index_has_field('templatelinks', 'tl_namespace', 'tl_from') ||
+		!index_has_field('imagelinks', 'il_to', 'il_from'))
+	{	
+		dbsource( archive( 'patch-backlinkindexes.sql' ) );
+	}
+}
+
 function do_all_updates( $doShared = false ) {
 	global $wgNewTables, $wgNewFields, $wgRenamedTables, $wgSharedDB, $wgDatabase, $wgDBtype;
 
@@ -860,6 +886,8 @@ function do_all_updates( $doShared = false ) {
 	do_page_random_update(); flush();
 	
 	do_rc_indices_update(); flush();
+	
+	do_backlinking_indices_update(); flush();
 
 	initialiseMessages(); flush();
 }