Database
db={"A":[{_id:"1",status:"Report",type:"Academy",rating:"Excellent",ReportNo:"A1"},{_id:"2",status:"Open",type:"Academy",rating:"",ReportNo:""},{_id:"3",status:"Draft",type:"Academy",rating:"",ReportNo:""},{_id:"4",status:"Report",type:"Academy",rating:"Great",ReportNo:"A4"}],"B":[{_id:"98",status:"Archived",type:"Academy",rating:"So So",ReportNo:"X2"},{_id:"99",status:"Archived",type:"Academy",rating:"Great",ReportNo:"X1"}]}
Query
db.A.aggregate([{"$match":{status:"Report"}},{"$unionWith":{"coll":"B"}}])