Yes, the idea is each ordering key is assigned to a single subscriber client, and all messages for that key are sent in order to that client. There is effective

Yes, the idea is each ordering key is assigned to a single subscriber client, and all messages for that key are sent in order to that client. There is effectively a cursor which is advanced by acking. When we reassign the key to another client, we replay all messages starting from the cursor. Disclaimer: I work on Cloud Pub/Sub