mongodb有个地方看不懂

Question

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

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

返回的是什么?
__________________________________________后来补充______________________________________________

逻辑是
在counters中查处某个的表名例如(aaa_aaa)的seq
然后将这个表(aaa_aaa)的seq存入该表(aaa_aaa)中的id值

Answer 1

$inc 在mongo里面就是自增1,所以结果每次自增1

Answer 2

counters集合中"_id"属性为$name的文档的seq+1