Database

[{query_a:[{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_a":"1"},{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_a":"2"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"3"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"4"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"5"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"6"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"7"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"8"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"9"}],query_b:[{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_b":"10"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_b":"11"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_b":"12"}],query_c:[{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf",},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6",},{"ID":"0aa73508-c862-7224-531e-b0983cd98aec",}]}]

Query

db.collection.aggregate([{"$project":{"union":{"$setUnion":["$query_a","$query_b"]}}},{"$unwind":"$union"},{"$group":{"_id":"$union.ID","date_a":{"$addToSet":"$union.date_a"},"date_b":{"$addToSet":"$union.date_b"}}},{"$unwind":"$date_a"},{"$unwind":"$date_b"},{"$project":{"_id":1,"date_a":"$date_a","date_b":"date_b","diff":{"$subtract":[{"$toInt":"$date_b"},{"$toInt":"$date_a"}]}}},{"$match":{"diff":{"$gt":0,"$lte":20}}},])

Result