Gazelle/sections/userhistory/catchup.php

<?
authorize();
if (($UserSubscriptions = $Cache->get_value('subscriptions_user_'.$LoggedUser['ID'])) === false) {
	$DB->query('
		SELECT TopicID
		FROM users_subscriptions
		WHERE UserID = '.db_string($LoggedUser['ID']));
	if ($UserSubscriptions = $DB->collect(0)) {
		$Cache->cache_value('subscriptions_user_'.$LoggedUser['ID'], $UserSubscriptions, 0);
	}
}
if (!empty($UserSubscriptions)) {
	$DB->query("
		INSERT INTO forums_last_read_topics (UserID, TopicID, PostID)
			SELECT '$LoggedUser[ID]', ID, LastPostID
			FROM forums_topics
			WHERE ID IN (".implode(',', $UserSubscriptions).')
		ON DUPLICATE KEY UPDATE PostID = LastPostID');
}
$Cache->delete_value('subscriptions_user_new_'.$LoggedUser['ID']);
header('Location: userhistory.php?action=subscriptions');
?>