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db.collection.aggregate([{"$match":{"date":{"$gte":ISODate("2019-01-01T00:00:00Z"),"$lte":ISODate("2019-12-31T23:59:59Z")}}},{$addFields:{month:{$month:"$date"}}},{$group:{_id:{vendor:"$companyVendorId",month:"$month"},amount:{$sum:"$amount"}}},{$sort:{amount:-1}},{$group:{_id:"$_id.month",top:{$push:{companyVendorId:"$_id.vendor",amount:"$amount",month:"$_id.month"}}}},{$project:{top:{$slice:["$top",2]}}},{$unwind:"$top"},{$replaceRoot:{newRoot:"$top"}},{$sort:{month:1,amount:-1}}])