Re: Single transaction in the tablesync worker?

On Fri, Jan 29, 2021 at 4:07 PM Peter Smith <smithpb2250@gmail.com> wrote:
>
>
> Differences from v21:
> + Patch is rebased to latest OSS HEAD @ 29/Jan.
> + Includes new code as suggested [ak0128] to ensure no dangling slots
> at Drop/AlterSubscription.
> + Removes the slot/origin cleanup down by process interrupt logic
> (cleanup_at_shutdown function).
> + Addresses some minor review comments.
>

I have made the below changes in the patch. Let me know what you think
about these?
1. It was a bit difficult to understand the code in DropSubscription
so I have rearranged the code to match the way we are doing in HEAD
where we drop the slots at the end after finishing all the other
cleanup.
2. In AlterSubscription_refresh(), we can't allow workers to be
stopped at commit time as we have already dropped the slots because
the worker can access the dropped slot. We need to stop the workers
before dropping slots. This makes all the code related to
logicalrep_worker_stop_at_commit redundant.
3. In AlterSubscription_refresh(), we need to acquire the lock on
pg_subscription_rel only when we try to remove any subscription rel.
4. Added/Changed quite a few comments.

-- 
With Regards,
Amit Kapila.