db={"test":[{"_id":ObjectId("64050396a27f4d08e8c3a0d4"),"a":10,"b":4444},{"_id":ObjectId("640504d3781e448660488d79"),"a":1000,"b":4444,"d":4444}]}

db.test.update({"a":1000},[{$set:{"a.v":2}},{$set:{"a":2}}])