public function flushAccumInsert()
    {
        if ($this->accum === null) {
            return 0;
        }
        $count = count($this->accum);
        if ($count > 0) {
            $this->multiInsert($this->accum, true);
        }
        $this->accum = null;
        $this->lastIdAccum = null;
        $this->sizeAccum = null;
        return $count;
    }