chain mapreduce after pipe?

[Jiang Yu]

how to run a aggregate and then apply a mapreduce in result?

pipe := []bson.D{...}

db.C(name).Pipe(pipe). ?

i knew that find query can chain mapreduce!

However pipe?

[Žygimantas Stauga]

https://docs.mongodb.org/manual/core/map-reduce/

There is no way to pipe some executed command results (find, aggregate, whatever) to map reduce. You can try store aggregation result in temporary collection, and then run map reduce there. Of course performance should be poor.

"i knew that find query can chain mapreduce!"

I think only query part are used.