perf(upgrade): speeds up migrating remember me codes

The Remember me cookie implementation has been improved by moving codes
to a separate table. This performs that migration in one query.

Fixes #6204

engine/lib/upgrades/2013062200-1.9.0_dev-new_remember_me_table-da1bfc6f36c7952e.php

@@ -11,33 +11,26 @@
 
 // create remember me table
 $query1 = <<<SQL
-CREATE TABLE IF NOT EXISTS `{$db_prefix}users_remember_me_cookies` (
-  `code` varchar(32) NOT NULL,
-  `guid` bigint(20) unsigned NOT NULL,
-  `timestamp` int(11) unsigned NOT NULL,
-  PRIMARY KEY (`code`),
-  KEY `timestamp` (`timestamp`)
-) ENGINE=MyISAM DEFAULT CHARSET=utf8;
+	CREATE TABLE IF NOT EXISTS `{$db_prefix}users_remember_me_cookies` (
+	  `code` varchar(32) NOT NULL,
+	  `guid` bigint(20) unsigned NOT NULL,
+	  `timestamp` int(11) unsigned NOT NULL,
+	  PRIMARY KEY (`code`),
+	  KEY `timestamp` (`timestamp`)
+	) ENGINE=MyISAM DEFAULT CHARSET=utf8;
 SQL;
 update_data($query1);
 
 // move codes
-$ia = elgg_set_ignore_access(true);
-$options = array(
-	'type' => 'user',
-	'limit' => 0,
-	'selects' => array("u.code as code"),
-	'joins' => array("JOIN {$db_prefix}users_entity u ON e.guid = u.guid"),
-);
-$batch = new ElggBatch('elgg_get_entities', $options);
-foreach ($batch as $entity) {
-	$code = $entity->getVolatileData('select:code');
-	if ($code) {
-		_elgg_add_remember_me_cookie($entity, $code);
-	}
-}
-elgg_set_ignore_access($ia);
+$time = time();
+$query2 = <<<SQL
+	INSERT INTO {$db_prefix}users_remember_me_cookies (`code`, `guid`, `timestamp`)
+	SELECT `code`, `guid`, $time
+	FROM {$db_prefix}users_entity
+	WHERE `code` != ''
+SQL;
+update_data($query2);
 
 // drop code from users table
-$query2 = "ALTER TABLE {$db_prefix}users_entity DROP code";
-update_data($query2);
+$query3 = "ALTER TABLE {$db_prefix}users_entity DROP `code`";
+update_data($query3);