[{type:"partial",jobId:"121",browser:"chrome",status:"true",jobName:"one"},{type:"partial",jobId:"122",browser:"chrome",status:"false",jobName:"two"},{type:"partial",jobId:"121",browser:"firefox",status:"false",jobName:"one"},{type:"partial",jobId:"122",browser:"firefox",status:"true",jobName:"two"},{type:"full",jobId:"123",browser:"chrome",status:"true",jobName:"three"},{type:"full",jobId:"123",browser:"chrome",status:"true",jobName:"three"},{type:"full",jobId:"123",browser:"chrome",status:"false",jobName:"three"},{type:"full",jobId:"124",browser:"firefox",status:"false",jobName:"four"},]

db.collection.aggregate([{$match:{jobId:{"$exists":true}}},{$sort:{_id:-1}},{$group:{_id:{type:"$type",browser:"$browser",jobId:"$jobId"},results:{$push:{jobName:"$jobName",status:"$status",type:"$type",jobId:"$jobId"}}}},{$addFields:{results:{$slice:["$results",30]}}},{$group:{_id:"$_id.browser",results:{$push:{results:"$results"}}}},])