RE: Perform streaming logical transactions by background workers and parallel apply

On Tue, Oct 25, 2022 2:56 PM Wang, Wei/王 威 <wangw(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Tues, Oct 25, 2022 at 14:28 PM Peter Smith <smithpb2250(at)gmail(dot)com>
> wrote:
> > FYI - After a recent push, the v40-0001 patch no longer applies on the
> > latest HEAD.
> >
> > [postgres(at)CentOS7-x64 oss_postgres_misc]$ git apply
> > ../patches_misc/v40-0001-Perform-streaming-logical-transactions-by-
> > parall.patch
> > error: patch failed: src/backend/replication/logical/launcher.c:54
> > error: src/backend/replication/logical/launcher.c: patch does not apply
>
> Thanks for your reminder.
>
> I just rebased the patch set for review.
> The new patch set will be shared later when the comments in this thread are
> addressed.
>

I tried to write a draft patch to force streaming every change instead of
waiting until logical_decoding_work_mem is exceeded, which could help to test
streaming parallel. Attach the patch. This is based on v41-0001 patch.

With this patch, I saw a problem that the subscription option "origin" doesn't
work when using streaming parallel. That's because when the parallel apply
worker writing the WAL for the changes, replorigin_session_origin is
InvalidRepOriginId. In current patch, origin can be active only in one process
at-a-time.

To fix it, maybe we need to remove this restriction, like what we did in the old
version of patch.

Regards
Shi yu