Re: Stopping logical replication protocol

Fair enough. Though I don't understand why you'd be doing this often enough that you'd care about reopening connections. What is the problem you are trying to solve with this? The underlying reason you need this change?

First reason it clear API in pgjdc. Second reason it ability fast enough rollack to one of the previous LSN and repeat it. My use case for second reason - I have logical decoding extension that prepare only data as key-value pair without information about (insert, update, delete) for example if it delete as key I use primary key for table and as value null. Via pgjdc by replication protocol connects receiver data, consumer group changes to batch and send it to Kafka. If some problem occurs during delivery to kafka consumer, I should stop current replication, go back to success LSN and repeat all messages from success LSN. I think it operation can be quite common, but reopen connection or not stopping replication will increase latency.

Anyway, here's a draft patch that does the parts other than the reorder buffer processing stop. It passes 'make check' and the src/test/recovery tests, but I haven't written anything to verify the client-initiated abort handling. You have test code for this and I'd be interested to see the results.

What about keepAlive package when we already send/receive CopyDone? Is It really necessary?

I think it's worth making the next step, where you allow reorder buffer commit processing to be interrupted, into a separate patch on top of this one. They're two separate changes IMO.

We will continue in the current thread, or new? I interesting in both patch for my solution and pgjbc driver.