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  * @file
  23  * @ingroup Maintenance
  24  */
  25
  26 require_once __DIR__ . '/Maintenance.php';
  27
  28 /**
  29  * Maintenance script to run a database query in batches and wait for slaves.
  30  *
  31  * @ingroup Maintenance
  32  */
  33 class BatchedQueryRunner extends Maintenance {
  34         public function __construct() {
  35                 parent::__construct();
  36                 $this->addDescription(
  37                         "Run a query repeatedly until it affects 0 rows, and wait for slaves in between.\n" .
  38                                 "NOTE: You need to set a LIMIT clause yourself." );
  39         }
  40
  41         public function execute() {
  42                 if ( !$this->hasArg() ) {
  43                         $this->error( "No query specified. Specify the query as a command line parameter.", true );
  44                 }
  45
  46                 $query = $this->getArg();
  47                 $n = 1;
  48                 $dbw = $this->getDB( DB_MASTER );
  49                 do {
  50                         $this->output( "Batch $n: " );
  51                         $n++;
  52                         $dbw->query( $query, __METHOD__ );
  53                         $affected = $dbw->affectedRows();
  54                         $this->output( "$affected rows\n" );
  55                         wfWaitForSlaves();
  56                 } while ( $affected > 0 );
  57         }
  58
  59         public function getDbType() {
  60                 return Maintenance::DB_ADMIN;
  61         }
  62 }
  63
  64 $maintClass = "BatchedQueryRunner";
  65 require_once RUN_MAINTENANCE_IF_MAIN;