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Backwards Compatibility:
Fully Compatible
Sprint:
QO 2021-09-06, Query Optimization 2021-08-09, QO 2021-09-20, QO 2021-10-04, QO 2021-10-18, QO 2021-11-01, QO 2021-08-23
Case:
Confidence Status:
None
Work Order:
3

Currently $filter expression will return all matching array elements of its input.

This is a request to add a "limit" option which caps the number of matches returned.

{$filter:{
    input:[1,2,3,10,11,12,15],
    cond:{$lt:["$$this", 13]},
    limit: 2
}}
// result
[1,2]

depends on

SERVER-59303 Support limit expression for $filter in SBE

is related to

SERVER-25957 Optimize $filter + $arrayElemAt to avoid scanning entire array