Horton
Menu

Re: Assertion failure in SnapBuildInitialSnapshot()

Masahiko Sawada <sawada.mshk@gmail.com>

View thread
From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Thomas Munro <thomas.munro@gmail.com>
Date: 2023-01-31T12:37:58Z
Lists: pgsql-hackers

Attachments

On Tue, Jan 31, 2023 at 3:59 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Tue, Jan 31, 2023 at 3:56 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Tue, Jan 31, 2023 at 11:12 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > On Mon, Jan 30, 2023 at 9:41 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > I've attached patches for HEAD and backbranches. Please review them.
> > >
> >
> > Shall we add a comment like the one below in
> > ReplicationSlotsComputeRequiredXmin()?
> > diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
> > index f286918f69..e28d48bca7 100644
> > --- a/src/backend/replication/slot.c
> > +++ b/src/backend/replication/slot.c
> > @@ -840,6 +840,13 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
> >
> >         Assert(ReplicationSlotCtl != NULL);
> >
> > +       /*
> > +        * It is possible that by the time we compute the agg_xmin
> > here and before
> > +        * updating replication_slot_xmin, the CreateInitDecodingContext() will
> > +        * compute and update replication_slot_xmin. So, we need to acquire
> > +        * ProcArrayLock here to avoid retreating the value of
> > replication_slot_xmin.
> > +        */
> > +
>
> Agreed. It looks good to me.

Attached updated patches.

Regards,

-- 
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix a race condition in updating procArray->replication_slot_xmin.

  2. Don't retreat slot's confirmed_flush LSN.

  3. Add additional checks while creating the initial decoding snapshot.