Make updateCollation.php a bit less murderous for WMF databases:

* Don't run a COUNT(*) query on what's potentially the entire categorylinks table on enwiki (hundreds of millions of rows). Put it in a miser mode check
* Wait for DB replication to catch up before processing the next batch. Implemented LoadBalancer::waitAll() for this purpose, which should behave more nicely than wfWaitForSlaves()

diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index 847d834..5f2af19 100644 (file)
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -338,6 +338,18 @@ class LoadBalancer {
                }
                wfProfileOut( __METHOD__ );
        }
+       
+       /**
+        * Set the master wait position and wait for ALL slaves to catch up to it
+        */
+       public function waitForAll( $pos ) {
+               wfProfileIn( __METHOD__ );
+               $this->mWaitForPos = $pos;
+               for ( $i = 1; $i < count( $this->mServers ); $i++ ) {
+                       $this->doWait( $i );
+               }
+               wfProfileOut( __METHOD__ );
+       }
 
        /**
         * Get any open connection to a given server index, local or foreign

diff --git a/maintenance/updateCollation.php b/maintenance/updateCollation.php
index 2985add..6631557 100644 (file)
--- a/maintenance/updateCollation.php
+++ b/maintenance/updateCollation.php
@@ -45,9 +45,16 @@ TEXT;
                $this->addOption( 'force', 'Run on all rows, even if the collation is ' . 
                        'supposed to be up-to-date.' );
        }
+       
+       public function syncDBs() {
+               $lb = wfGetLB();
+               $dbw = $lb->getConnection( DB_MASTER );
+               $pos = $dbw->getMasterPos();
+               $lb->waitForAll( $pos );
+       }
 
        public function execute() {
-               global $wgCategoryCollation;
+               global $wgCategoryCollation, $wgMiserMode;
 
                $dbw = wfGetDB( DB_MASTER );
                $force = $this->getOption( 'force' );
@@ -55,30 +62,32 @@ TEXT;
                $options = array( 'LIMIT' => self::BATCH_SIZE );
 
                if ( $force ) {
-                       $collationConds = array();
                        $options['ORDER BY'] = 'cl_from, cl_to';
                } else {
                        $collationConds = array( 0 => 
                                'cl_collation != ' . $dbw->addQuotes( $wgCategoryCollation ) );
 
-                       $count = $dbw->selectField(
-                               'categorylinks',
-                               'COUNT(*)',
-                               $collationConds,
-                               __METHOD__
-                       );
+                       if ( !$wgMiserMode ) {
+                               $count = $dbw->selectField(
+                                       'categorylinks',
+                                       'COUNT(*)',
+                                       $collationConds,
+                                       __METHOD__
+                               );
 
-                       if ( $count == 0 ) {
-                               $this->output( "Collations up-to-date.\n" );
-                               return;
+                               if ( $count == 0 ) {
+                                       $this->output( "Collations up-to-date.\n" );
+                                       return;
+                               }
+                               $this->output( "Fixing collation for $count rows.\n" );
                        }
-                       $this->output( "Fixing collation for $count rows.\n" );
                }
 
                $count = 0;
                $row = false;
                $batchConds = array();
                do {
+                       $this->output( 'Processing next ' . self::BATCH_SIZE . ' rows... ');
                        $res = $dbw->select(
                                array( 'categorylinks', 'page' ),
                                array( 'cl_from', 'cl_to', 'cl_sortkey_prefix', 'cl_collation',
@@ -140,6 +149,8 @@ TEXT;
 
                        $count += $res->numRows();
                        $this->output( "$count done.\n" );
+                       
+                       $this->syncDBs();
                } while ( $res->numRows() == self::BATCH_SIZE );
        }
 }