maintenance script to run linter extension namespace migration

*  It should be safe to automatically run during wiki update on
    3rd party wikis, and requires manual invocation on enwiki

 * The namespace migrate for enwiki will be run by an admin during
   a backport window so the process can be monitored and may run
   for a day potentially.

Bug: T299612
Change-Id: I19091a6f177e8b67d80c0b8f46782929d2e951d4

maintenance/migrateNamespace.php

@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * Maintenance script that migrates the page table page_namespace field values
+ * to the linter table linter_namespace field to improve linter search performance.
+ * note: This should be run once the namespace write functionality in linter
+ *   recordLintJob has been enabled by setting LinterWriteNamespaceColumnStage true.
+ * note: This code is based on migrateRevisionActorTemp.php and migrateLinksTable.php
+ */
+
+use MediaWiki\Linter\Database;
+
+$IP = getenv( 'MW_INSTALL_PATH' );
+if ( $IP === false ) {
+	$IP = __DIR__ . '/../../..';
+}
+require_once "$IP/maintenance/Maintenance.php";
+
+class MigrateNamespace extends LoggedUpdateMaintenance {
+
+	/**
+	 * @inheritDoc
+	 */
+	public function __construct() {
+		parent::__construct();
+		$this->requireExtension( 'Linter' );
+		$this->addDescription(
+			'Copy the namespace data from the page table into the linter table'
+		);
+		$this->addOption(
+			'sleep',
+			'Sleep time (in seconds) between every batch. Default: 1 seconds',
+			false,
+			true
+		);
+		$this->setBatchSize( 1000 );
+	}
+
+	/**
+	 * The Linter migrate namespace script can take a day to run using: --wiki enwiki
+	 * @inheritDoc
+	 */
+	protected function doDBUpdates() {
+		$config = $this->getConfig();
+		$enableMigrateNamespaceStage = $config->get( 'LinterMigrateNamespaceStage' );
+		if ( !$enableMigrateNamespaceStage ) {
+			$this->output( "LinterMigrateNamespaceStage config value is false, code is disabled, exiting\n" );
+			return false;
+		}
+
+		$this->output( "Running linter migrate namespace function, this may take a while\n" );
+
+		$batchSize = $this->getBatchSize();
+		$sleep = (int)$this->getOption( 'sleep', 1 );
+
+		$dbw = self::getDB( DB_PRIMARY );
+		if ( !$dbw->fieldExists( 'linter', 'linter_namespace', __METHOD__ ) ) {
+			$this->output( "Run update.php to add linter_namespace field to the linter table.\n" );
+			return false;
+		}
+
+		$this->output( "Migrating the page table page_namespace field to the linter table...\n" );
+
+		$updated = Database::migrateNamespace( $batchSize, $batchSize, $sleep, false );
+
+		$this->output( "Completed migration of page_namespace data to the linter table, $updated rows updated.\n" );
+
+		return true;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	protected function getUpdateKey() {
+		return 'migrate namespace id from page to linter table';
+	}
+}
+
+$maintClass = MigrateNamespace::class;
+require_once RUN_MAINTENANCE_IF_MAIN;