Re: GUC-ify walsender MAX_SEND_SIZE constant

Hey folks,

Any news, comments, etc. about this thread?

Best regards
Majid Garoosi

On Mon, 12 Feb 2024 at 01:10, Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Sun, Feb 11, 2024 at 04:32:20PM +0330, Majid Garoosi wrote:
> > On Fri, 9 Feb 2024 at 22:33, Andres Freund <andres(at)anarazel(dot)de> wrote:
> >> The way we read the WAL data is perfectly prefetchable by the the OS,
> so I
> >> wouldn't really expect gains here. Have you actually been able to see a
> >> performance benefit by increasing MAX_SEND_SIZE?
> >
> > Yes, I have seen a huge performance jump. Take a look at here
> > <
> https://www.postgresql.org/message-id/CAFWczPvi_5FWH%2BJTqkWbi%2Bw83hy%3DMYg%3D2hKK0%3DJZBe9%3DhTpE4w%40mail.gmail.com
> >
> > for
> > more info.
>
> Yes, I can get the idea that grouping more replication messages in
> one shot can be beneficial in some cases while being
> environment-dependent, though I also get the point that we cannot
> simply GUC-ify everything either. I'm OK with this one at the end,
> because it is not performance critical.
>
> Note that it got lowered to the current value in ea5516081dcb to make
> it more responsive, while being half a WAL segment in 40f908bdcdc7
> when WAL senders have been introduced in 2010. I cannot pinpoint the
> exact thread that led to this change, but I'm adding Fujii-san and
> Heikki in CC for comments.
> --
> Michael
>