maintenance/runBatchedQuery.php

   1 <?php
   2 /**
   3  * Run a database query in batches and wait for slaves. This is used on large
   4  * wikis to prevent replication lag from going through the roof when executing
   5  * large write queries.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  * http://www.gnu.org/copyleft/gpl.html
  21  *
  22  * @ingroup Maintenance
  23  */
  24
  25 require_once( dirname( __FILE__ ) . '/Maintenance.php' );
  26
  27 class BatchedQueryRunner extends Maintenance {
  28         public function __construct() {
  29                 parent::__construct();
  30                 $this->mDescription = "Run a query repeatedly until it affects 0 rows, and wait for slaves in between.\n" .
  31                                 "NOTE: You need to set a LIMIT clause yourself.";
  32                 $this->addOption( 'wait', "Wait for replication lag to go down to this value. Default: 5", false, true );
  33         }
  34
  35         public function execute() {
  36                 if ( !$this->hasArg() )
  37                         $this->error( "No query specified. Specify the query as a command line parameter.", true );
  38
  39                 $query = $this->getArg();
  40                 $wait = $this->getOption( 'wait', 5 );
  41                 $n = 1;
  42                 $dbw = wfGetDb( DB_MASTER );
  43                 do {
  44                         $this->output( "Batch $n: " );
  45                         $n++;
  46                         $dbw->query( $query );
  47                         $affected = $dbw->affectedRows();
  48                         $this->output( "$affected rows\n" );
  49                         wfWaitForSlaves( $wait );
  50                 } while ( $affected > 0 );
  51         }
  52
  53         public function getDbType() {
  54                 return Maintenance::DB_ADMIN;
  55         }
  56 }
  57
  58
  59 $maintClass = "BatchedQueryRunner";
  60 require_once( DO_MAINTENANCE );