119 lines
4.0 KiB
PHP
119 lines
4.0 KiB
PHP
<?php
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/**
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* Run a database query in batches and wait for replica DBs. This is used on large
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* wikis to prevent replication lag from going through the roof when executing
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* large write queries.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Maintenance
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*/
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require_once __DIR__ . '/Maintenance.php';
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use MediaWiki\MediaWikiServices;
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use Wikimedia\Rdbms\IDatabase;
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/**
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* Maintenance script to run a database query in batches and wait for replica DBs.
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*
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* @ingroup Maintenance
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*/
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class RunBatchedQuery extends Maintenance {
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public function __construct() {
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parent::__construct();
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$this->addDescription(
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"Run an update query on all rows of a table. " .
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"Waits for replicas at appropriate intervals." );
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$this->addOption( 'table', 'The table name', true, true );
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$this->addOption( 'set', 'The SET clause', true, true );
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$this->addOption( 'where', 'The WHERE clause', false, true );
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$this->addOption( 'key', 'A column name, the values of which are unique', true, true );
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$this->addOption( 'batch-size', 'The batch size (default 1000)', false, true );
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$this->addOption( 'db', 'The database name, or omit to use the current wiki.', false, true );
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}
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public function execute() {
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$table = $this->getOption( 'table' );
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$key = $this->getOption( 'key' );
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$set = $this->getOption( 'set' );
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$where = $this->getOption( 'where', null );
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$where = $where === null ? [] : [ $where ];
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$batchSize = $this->getOption( 'batch-size', 1000 );
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$dbName = $this->getOption( 'db', null );
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if ( $dbName === null ) {
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$dbw = $this->getDB( DB_PRIMARY );
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} else {
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$lbf = MediaWiki\MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
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$lb = $lbf->getMainLB( $dbName );
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$dbw = $lb->getConnection( DB_PRIMARY, [], $dbName );
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}
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$selectConds = $where;
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$prevEnd = false;
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$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
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$n = 1;
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do {
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$this->output( "Batch $n: " );
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$n++;
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// Note that the update conditions do not rely on atomicity of the
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// SELECT query in order to guarantee that all rows are updated. The
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// results of the SELECT are merely a partitioning hint. Simultaneous
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// updates merely result in the wrong number of rows being updated
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// in a batch.
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$res = $dbw->select( $table, $key, $selectConds, __METHOD__,
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[ 'ORDER BY' => $key, 'LIMIT' => $batchSize ] );
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if ( $res->numRows() ) {
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$res->seek( $res->numRows() - 1 );
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$row = $res->fetchObject();
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$end = $dbw->addQuotes( $row->$key );
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$selectConds = array_merge( $where, [ "$key > $end" ] );
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$updateConds = array_merge( $where, [ "$key <= $end" ] );
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} else {
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$updateConds = $where;
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$end = false;
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}
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if ( $prevEnd !== false ) {
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$updateConds = array_merge( [ "$key > $prevEnd" ], $updateConds );
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}
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$query = "UPDATE " . $dbw->tableName( $table ) .
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" SET " . $set .
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" WHERE " . $dbw->makeList( $updateConds, IDatabase::LIST_AND );
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$dbw->query( $query, __METHOD__ );
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$prevEnd = $end;
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$affected = $dbw->affectedRows();
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$this->output( "$affected rows affected\n" );
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$lbFactory->waitForReplication();
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} while ( $res->numRows() );
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}
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public function getDbType() {
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return Maintenance::DB_ADMIN;
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}
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}
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$maintClass = RunBatchedQuery::class;
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require_once RUN_MAINTENANCE_IF_MAIN;
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