Re: wal segment size

On 12/17/25 08:10, Colin 't Hart wrote:
> Thanks Laurenz, that confirms what I was assuming. Archiving is via
> pgbackrest to a backup server, over SSH. Approx 750ms to archive each
> segment is crazy -- I'll check compression parameters too.

How much of that time is network travel?

What are the configuration settings for the archiving portion of pgBackRest?

>
> Any reason not to bump it up to 1GB? Or is that overkill?
>
> /Colin
>
> On Wed, 17 Dec 2025 at 16:25, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at
> <mailto:laurenz(dot)albe(at)cybertec(dot)at>> wrote:
>
> On Wed, 2025-12-17 at 16:13 +0100, Colin 't Hart wrote:
> > I see very little advice on tuning WAL segment size.
> >
> > One of my clients has a few datawarehouses at around 8 - 16 TB
> >
> > On one of the nodes there are approx 15000 WAL segments of 16MB
> each, totalling
> > approx 230GB. The archiver is archiving approx one per second, so
> approx 4 hours to clear.
> >
> > Would we gain anything by bumping the WAL segment size?
>
> Very likely yes, if the problem is the overhead of starting the
> archive_command.
>
> Another thing that can slow down archiving is if you compress these
> segments
> too aggressively.
>
> Yours,
> Laurenz Albe
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com