Mongodb has a place to look at

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

What was returned?
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ was added later

The logic is
Investigate and deal with some table name in counters, such as seq of (aaa_aaa)
Seq of this table (aaa_aaa) is then stored in the id value in this table (aaa_aaa)

$incIn mongo, it increases by 1, so the result increases by 1 each time.