// clean up oc_share table from files which are no longer exists
if (version_compare($installedVersion, '0.3.4', '<')) {
// get all shares where the original file no longer exists
$findShares = \OC_DB::prepare('SELECT `file_source` FROM `*PREFIX*share` LEFT JOIN `*PREFIX*filecache` ON `file_source` = `*PREFIX*filecache`.`fileid` WHERE `*PREFIX*filecache`.`fileid` IS NULL');