Database
[{"data":{"id":"123","name":"delta1"},"property_data":[{"ser_name":"Insights","ser_value":"10000"},{"ser_name":"plans","ser_value":"50000"}]}]
Query
db.collection.aggregate([{$project:{property_data:{"$concatArrays":["$property_data",["$data"]]}}},{$unwind:"$property_data"},{$replaceRoot:{newRoot:{property_data:"$property_data"}}}])