Re: Parallel vacuum workers prevent the oldest xmin from advancing

On Wed, Oct 6, 2021 at 12:41 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> Hi all,
>
> A customer reported that during parallel index vacuum, the oldest xmin
> doesn't advance. Normally, the calculation of oldest xmin
> (ComputeXidHorizons()) ignores xmin/xid of processes having
> PROC_IN_VACUUM flag in MyProc->statusFlags. But since parallel vacuum
> workers don’t set their statusFlags, the xmin of the parallel vacuum
> worker is considered to calculate the oldest xmin. This issue happens
> from PG13 where the parallel vacuum was introduced. I think it's a
> bug.
>

I agree. Your patch seems to be in the right direction but I haven't
tested it yet. Feel free to register in the next CF to avoid
forgetting it.

--
With Regards,
Amit Kapila.