From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael.paquier@gmail.com>
Cc: Peter Geoghegan <pg@bowt.ie>
Cc: Wood, Dan <hexpert@amazon.com>
Cc: pgsql-bugs@postgresql.org <pgsql-bugs@postgresql.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Wong, Yi Wen <yiwong@amazon.com>
Subject: Re: Old row version in hot chain become visible after a freeze
Date: Tue, 12 Sep 2017 14:41:36 +0200
Message-ID: <20170912124136.kgasny22tjf7btdj@alvherre.pgsql> (raw)
In-Reply-To: <CAB7nPqSspx00vRNzXDR7=+=CjWsCY2sxUae6oY7EjwKiBNBd6Q@mail.gmail.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-bugs>
Michael Paquier wrote:
> On Tue, Sep 12, 2017 at 5:22 PM, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> > Michael Paquier wrote:
> >> On Mon, Sep 11, 2017 at 11:01 PM, Alvaro Herrera
> >> <alvherre@alvh.no-ip.org> wrote:
> >> > (I also threw in a small sleep between heap_page_prune and
> >> > HeapTupleSatisfiesVacuum while testing, just to widen the problem window
> >> > to hopefully make any remaining problems more evident.)
> >>
> >> I am understanding that you mean heap_prepare_freeze_tuple here
> >> instead of heap_page_prune.
> >
> > Hmm ... no, I meant adding a sleep after the page is pruned, before
> > HeapTupleSatisfiesVacuum call that determines the action with regards to
> > freezing.
>
> Well, I have tested both. With the test case of Dan adding a sleep
> after calling HeapTupleSatisfiesVacuum() helped in increasing the
> window. Of course feel free to correct me.
OK, great, thanks for testing.
> > I bet those are multixact values rather than garbage. You should see
> > HEAP_XMAX_IS_MULTI in t_infomask in those cases, and the values should
> > be near NextMultiXactId (make sure to checkpoint if you examine with
> > pg_controldata; I think it's easier to obtain it from shmem. Or you
> > could just use pg_get_multixact_members()).
>
> Yes, you're right. That's the case. So I guess that I don't have much
> complains about the patch as presented.
Thanks for the confirmation.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
--
Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-bugs
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-bugs@postgresql.org
Cc: alvherre@alvh.no-ip.org, michael.paquier@gmail.com, pg@bowt.ie, hexpert@amazon.com, andres@anarazel.de, yiwong@amazon.com
Subject: Re: Old row version in hot chain become visible after a freeze
In-Reply-To: <20170912124136.kgasny22tjf7btdj@alvherre.pgsql>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox