Pub/Sub message ordering should also support stickiness by key
Similar to kafka, I expect message ordering key to validate that same subscriber gets all messages tagged by a specific message key.
If I have to aggregate data by message key, currently I can do it only by a service that cannot be scaled. I would like to be able to scale my service, knowing that messages of the same key will always be received by the same service instance.
(Tested it by writing messages to a topic, all with the same ordering key. Tried to read from two service instances, using same ordering-enabled subscription. While most of the messages received by one of the instances, some of them received by the second.)