runBatchedQuery.php

Go to the documentation of this file.

<?php
require_once __DIR__ . '/Maintenance.php';
 
use Wikimedia\Rdbms\IDatabase;
 
class RunBatchedQuery extends Maintenance {
    public function __construct() {
        parent::__construct();
        $this->addDescription(
            "Run an update query on all rows of a table. " .
            "Waits for replicas at appropriate intervals." );
        $this->addOption( 'table', 'The table name', true, true );
        $this->addOption( 'set', 'The SET clause', true, true );
        $this->addOption( 'where', 'The WHERE clause', false, true );
        $this->addOption( 'key', 'A column name, the values of which are unique', true, true );
        $this->addOption( 'batch-size', 'The batch size (default 1000)', false, true );
        $this->addOption( 'db', 'The database name, or omit to use the current wiki.', false, true );
    }
 
    public function execute() {
        $table = $this->getOption( 'table' );
        $key = $this->getOption( 'key' );
        $set = $this->getOption( 'set' );
        $where = $this->getOption( 'where', null );
        $where = $where === null ? [] : [ $where ];
        $batchSize = $this->getOption( 'batch-size', 1000 );
 
        $dbName = $this->getOption( 'db', null );
        if ( $dbName === null ) {
            $dbw = $this->getDB( DB_MASTER );
        } else {
            $lbf = MediaWiki\MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
            $lb = $lbf->getMainLB( $dbName );
            $dbw = $lb->getConnection( DB_MASTER, [], $dbName );
        }
 
        $selectConds = $where;
        $prevEnd = false;
 
        $n = 1;
        do {
            $this->output( "Batch $n: " );
            $n++;
 
            // Note that the update conditions do not rely on atomicity of the
            // SELECT query in order to guarantee that all rows are updated. The
            // results of the SELECT are merely a partitioning hint. Simultaneous
            // updates merely result in the wrong number of rows being updated
            // in a batch.
 
            $res = $dbw->select( $table, $key, $selectConds, __METHOD__,
                [ 'ORDER BY' => $key, 'LIMIT' => $batchSize ] );
            if ( $res->numRows() ) {
                $res->seek( $res->numRows() - 1 );
                $row = $res->fetchObject();
                $end = $dbw->addQuotes( $row->$key );
                $selectConds = array_merge( $where, [ "$key > $end" ] );
                $updateConds = array_merge( $where, [ "$key <= $end" ] );
            } else {
                $updateConds = $where;
            }
            if ( $prevEnd !== false ) {
                $updateConds = array_merge( [ "$key > $prevEnd" ], $updateConds );
            }
 
            $query = "UPDATE " . $dbw->tableName( $table ) .
                " SET " . $set .
                " WHERE " . $dbw->makeList( $updateConds, IDatabase::LIST_AND );
 
            $dbw->query( $query, __METHOD__ );
 
            $prevEnd = $end;
 
            $affected = $dbw->affectedRows();
            $this->output( "$affected rows affected\n" );
            wfWaitForSlaves();
        } while ( $res->numRows() );
    }
 
    public function getDbType() {
        return Maintenance::DB_ADMIN;
    }
}
 
$maintClass = RunBatchedQuery::class;
require_once RUN_MAINTENANCE_IF_MAIN;