protected function _hasRefsInMM($key, $filter, $options, $ttl=0) {
		$fieldConf = $this->fieldConf[$key]['has-many'];
		$rel = $this->getRelInstance($fieldConf[0],null,$key,true);
		$hasSet = $rel->find($filter,$options,$ttl);
		$result = false;
		if ($hasSet) {
			$hasIDs = $hasSet->getAll('_id',true);
			$mmTable = $this->mmTable($fieldConf,$key);
			$pivot = $this->getRelInstance(null,array('db'=>$this->db,'table'=>$mmTable));
			$filter = [$key.' IN ?',$hasIDs];
			if ($fieldConf['isSelf']) {
				$filter[0].= ' OR '.$key.'_ref IN ?';
				$filter[] = $hasIDs;
			}
			$pivotSet = $pivot->find($filter,null,$ttl);
			if ($pivotSet) {
				$result = $pivotSet->getAll($fieldConf['relField'],true);
				if ($fieldConf['isSelf'])
					$result = array_merge($result,
						$pivotSet->getAll($fieldConf['relField'].'_ref',true));
				$result = array_diff(array_unique($result),$hasIDs);
			}
		}
		return $result;
	}