mongodb有個地方看不懂

Question

$collection = $this->_getCollection("counters");

$counter = $collection->findAndModify(
        array(
            "_id" => $name
        ),
        array(
            '$inc' => array(
                "seq" => 1
            )
        )
    );
    
    return $counter["seq"];
    
    
    

回傳的是什麼?
__________________________________________後來補充______________________________________________

邏輯是
在counters中查處某個的表名例如(aaa_aaa)的seq
然後將這個表(aaa_aaa)的seq存入該表(aaa_aaa)中的id值

Answer 1

$inc 在mongo裡面就是自增1,所以結果每次自增1

Answer 2

counters集合中"_id"屬性為$name的文檔的seq+1