[{"id":1,"contact":[{"isActive":"Y"},{"isActive":"Y"},{"isActive":"N"}]},{"id":2,"contact":[{"isActive":"Y"}]}]

db.collection.aggregate([{"$match":{"id":1}},{"$unwind":"$contact"},{"$match":{"contact.isActive":"Y"}},{"$group":{"_id":"$id","total":{"$sum":1}}}])