Re: Make default subscription streaming option as Parallel

vignesh C <vignesh21@gmail.com>

From: vignesh C <vignesh21@gmail.com>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-10-07T10:33:10Z
Lists: pgsql-hackers

Attachments

On Mon, 7 Oct 2024 at 12:26, Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> Dear Vignesh,
>
> > One key point to consider is that the lock on transaction objects will
> > be held for a longer duration when using streaming in parallel. This
> > occurs because the parallel apply worker initiates the transaction as
> > soon as streaming begins, maintaining the lock until the transaction
> > is fully completed. As a result, for long-running transactions, this
> > extended lock can hinder concurrent access that requires a lock.
>
> So, the current default is the most conservative and can run anywhere; your
> proposal is a bit optimistic, right?

Yes, that is correct.

> One comment for your patch;
> Shouldn't we add a streaming=off case for pg_dump test? You added lines but no one
> passes it.
>

Update existing pg_dump tests to cover the streaming options, the
attached patch has the changes for the same.

Regards,
Vignesh

Commits

  1. Change the default value of the streaming option to 'parallel'.