Re: Faulty HEAP_XMAX_LOCK_ONLY & HEAP_KEYS_UPDATED hintbit combination

From: Julien Rouhaud <rjuju123(at)gmail(dot)com>
To: Mahendra Singh Thalor <mahi6run(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Faulty HEAP_XMAX_LOCK_ONLY & HEAP_KEYS_UPDATED hintbit combination
Date: 2021-02-04 16:06:24
Message-ID: 20210204160624.GA22612@nol
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On Thu, Feb 04, 2021 at 08:34:13PM +0530, Mahendra Singh Thalor wrote:
> On Tue, 2 Feb 2021 at 09:51, Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
> >
> > On Mon, Feb 01, 2021 at 02:00:48PM -0300, Alvaro Herrera wrote:
> > > So I think that I misspoke earlier in this thread when I said this is a
> > > bug, and that the right fix here is to remove the Assert() and change
> > > amcheck to match.
> >
> > I'm attaching a patch to do so.
> Thanks Julien for the patch.
> Patch looks good to me and it is fixing the problem. I think we can
> register in CF.

Thanks for looking at it! I just created an entry for the next commitfest.

> >
> > Changing the name may be overkill, but claryfing the hint bit usage in
> > README.tuplock would definitely be useful, especially since the combination
> > isn't always produced. How about adding something like:
> >
> > This bit lives in t_infomask2. If set, indicates that the XMAX updated
> > this tuple and changed the key values, or it deleted the tuple.
> > + It can also be set in combination of HEAP_XMAX_LOCK_ONLY.
> > It's set regardless of whether the XMAX is a TransactionId or a MultiXactId.
> Make sense. Please can you update this?

Sure, done in attached v2!

Attachment Content-Type Size
v2-0001-Allow-HEAP_XMAX_LOCK_ONLY-and-HEAP_KEYS_UPDATED-c.patch text/plain 4.3 KB

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