mongodb - More granular limits in Mongo aggregate calls? -


i have query run on mongo. looks this:

db.getcollection('termstatistics').aggregate(     { $filter: { "kind": 0 } },     {         $group:         {             "_id": "$termid",             "count": {$sum: numberlong(1)}         }     },     { $sort: {"count": -1} },     { $limit: 100 } )

this gets count of each termid , gives me top 100 of them. however, i've got run same query each value of kind, of there several, because user wants top 100 each category. i'd avoid going mongo several times single query (the actual filter user-specific filtering, it's not reasonable cache results).

is possible combine these single aggregation call? kind of "limit per value of kind" or something?

edit: here sample documents. these little dumb, it's hard post thousands of documents interest them.... suppose i've got n copies of these (with varying _ids) each n between 1 , 1000:

{ kind: 0, termid: n }

plus i've got n of these, each n between 1 , 100:

{ kind: 1, termid: n }

what want top 100 termid each kind. kind: 0 [{ _id: 1000, count: 1000 }, ...{ _id: 901, count: 901 }] , kind: 1 [{ _id: 200, count: 200 }, ..., { _id: 101, count: 101 }].

this easy takes 2 aggregate calls (see above). nice 1 aggregate call , like following:

[     { kind: 0, data: [{ _id: 1000, count: 1000 }, ...{ _id: 901, count: 901 }]},     { kind: 1, data: [{ _id: 200, count: 200 }, ...{ _id: 101, count: 101 }]}, ]

if raise limit 200, won't kind: 1 because there enough common termids kind: 0, i'd need other kind of limit, or clever use of it.

hope that's more clear!

not 100% sure you're trying try grouping on "kind" field , term instead of using $match or $filter on first.

something like:

db.getcollection('termstatistics').aggregate(     {         $group: {             "_id": {                 "kind": "$kind",                 "term": "$termid"             },             "count": {                 $sum: numberlong(1)             }         }     },     { $sort: {"count": -1} },     { $limit: 100 } )

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