Does MongoDB's $in clause has any max limit in number of arguments

Question

When using MongoDB's $in clause with Aggregate , Does That has any max limit in number of arguments ?

for example

Model.aggregate(
        [
            { $match : 
                { '_Id' : 
                            {
                                $in : ids
                            }
                }
            } ,
            { $group : 
                {   _id : '$roomId' ,
                    maxdate: { $max: "$date"},
                }
            },
            {$sort: { maxdate: -1} },
            {$skip: skip},
            {$limit: limitNum }
        ]

In ids array , how many ids i can pass ?

Currently i am not facing any issue with ids length till 50,000 ... but for safe side wanted to know the max limit.

I have tried to search on Mongo doc , but didnt find anything.

Thanks in advance.

Answer 1

There is no limit to the number of arguments in the $in clause itself, however, the total query size is limited to 16MB as a query is just a BSON document. Depending on the type used for ids (see the BSON specification), you may start running into problems when your ids length is in the order of a few millions.