Re: Improve description of XLOG_RUNNING_XACTS

On Thu, Jul 21, 2022 at 4:29 PM Kyotaro Horiguchi
<horikyota(dot)ntt(at)gmail(dot)com> wrote:
>
> At Thu, 21 Jul 2022 11:21:09 +0900, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote in
> >
> >
> > On 2022/07/21 10:13, Masahiko Sawada wrote:
> > > Hi,
> > > I realized that standby_desc_running_xacts() in standbydesc.c doesn't
> > > describe subtransaction XIDs. I've attached the patch to improve the
> > > description.
> >
> > +1
> >
> > The patch looks good to me.
>
> The subxids can reach TOTAL_MAX_CACHED_SUBXIDS =
> PGPROC_MAX_CACHED_SUBXIDS(=64) * PROCARRAY_MAXPROCS. xact_desc_commit
> also shows subtransactions but they are at maximum 64. I feel like
> -0.3 if there's no obvious advantage showing them.

xxx_desc() functions are debugging purpose functions as they are used
by pg_waldump and pg_walinspect etc. I think such functions should
show all contents unless there is reason to hide them. Particularly,
standby_desc_running_xacts() currently shows subtransaction
information only when subtransactions are overflowed, which got me
confused when inspecting WAL records.

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/