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In-Reply-To: <46cc45e9-fddd-44bc-bcb3-96889aafd921@iki.fi>
From: wenhui qiu <qiuwenhuifx@gmail.com>
Date: Tue, 18 Nov 2025 09:47:45 +0800
Message-ID: 
 <CAGjGUA+iGwFS8MDCTSZg7-E_H792N8XWia=Q7tx4mE14T=r6xA@mail.gmail.com>
Subject: Re: POC: make mxidoff 64 bits
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Maxim Orlov <orlovmg@gmail.com>,
 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
 Alexander Korotkov <aekorotkov@gmail.com>,
	Postgres hackers <pgsql-hackers@lists.postgresql.org>
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Hi Heikki
> I don't think we need to support that case. I hope there are no clusters
> in that state still in the wild, and you can work around it by upgrading
> to 9.3.5 or above and letting autovacuum run. But I wonder if a
> pre-upgrade check with a better error message would still be worthwhile.
I think we believe it is now highly unlikely to find instances of version
9.3; all users are advised to upgrade to the latest version first.


Thanks

On Tue, Nov 18, 2025 at 12:35=E2=80=AFAM Heikki Linnakangas <hlinnaka@iki.f=
i> wrote:

> Here's yet another patch version. I spent the day reviewing this in
> detail and doing little cleanups here and there. I squashed the commits
> and wrote a proper commit message.
>
> One noteworthy refactoring is in pg_upgrade.c, to make it more clear (to
> me at least) how upgrade from version 9.2 and below now works. It was
> actually broken when I tested it. Not sure if I had broken it earlier or
> if it never worked, but in any case it works now.
>
> I also tested upgrading a cluster from an old minor version, < 9.3.5,
> where the control file has a bogus oldestMultiXid=3D=3D1 value (see commi=
t
> b6a3444fa6). As expected, you get a "could not open file" error:
>
> > Performing Upgrade
> > ------------------
> > Setting locale and encoding for new cluster                   ok
> > ...
> > Deleting files from new pg_multixact/members                  ok
> > Deleting files from new pg_multixact/offsets                  ok
> > Converting pg_multixact files
> > could not open file
> "/home/heikki/pgsql.93stable/data/pg_multixact/offsets/0000": No such fil=
e
> or directory
> > Failure, exiting
>
> I don't think we need to support that case. I hope there are no clusters
> in that state still in the wild, and you can work around it by upgrading
> to 9.3.5 or above and letting autovacuum run. But I wonder if a
> pre-upgrade check with a better error message would still be worthwhile.
>
>
> Ashutosh, you were interested in reviewing this earlier. Would you have
> a chance to review this now, before I commit it? Alexander, Alvaro,
> would you have a chance to take a final look too, please?
>
> - Heikki
>

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<div dir=3D"ltr">Hi Heikki<div>&gt; I don&#39;t think we need to support th=
at case. I hope there are no clusters<span class=3D"gmail-Apple-converted-s=
pace">=C2=A0</span><br>&gt; in that state still in the wild, and you can wo=
rk around it by upgrading<span class=3D"gmail-Apple-converted-space">=C2=A0=
</span><br>&gt; to 9.3.5 or above and letting autovacuum run. But I wonder =
if a<span class=3D"gmail-Apple-converted-space">=C2=A0</span><br>&gt; pre-u=
pgrade check with a better error message would still be worthwhile.<br></di=
v><div>I think we believe it is now highly unlikely to find instances of ve=
rsion 9.3; all users are advised to upgrade to the latest version first.</d=
iv><div><br></div><div><br></div><div><br></div><div><br></div><div>Thanks<=
/div></div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D=
"ltr" class=3D"gmail_attr">On Tue, Nov 18, 2025 at 12:35=E2=80=AFAM Heikki =
Linnakangas &lt;<a href=3D"mailto:hlinnaka@iki.fi">hlinnaka@iki.fi</a>&gt; =
wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0=
px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rg=
b(204,204,204);padding-left:1ex">Here&#39;s yet another patch version. I sp=
ent the day reviewing this in <br>
detail and doing little cleanups here and there. I squashed the commits <br=
>
and wrote a proper commit message.<br>
<br>
One noteworthy refactoring is in pg_upgrade.c, to make it more clear (to <b=
r>
me at least) how upgrade from version 9.2 and below now works. It was <br>
actually broken when I tested it. Not sure if I had broken it earlier or <b=
r>
if it never worked, but in any case it works now.<br>
<br>
I also tested upgrading a cluster from an old minor version, &lt; 9.3.5, <b=
r>
where the control file has a bogus oldestMultiXid=3D=3D1 value (see commit =
<br>
b6a3444fa6). As expected, you get a &quot;could not open file&quot; error:<=
br>
<br>
&gt; Performing Upgrade<br>
&gt; ------------------<br>
&gt; Setting locale and encoding for new cluster=C2=A0 =C2=A0 =C2=A0 =C2=A0=
 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0ok<br>
&gt; ...<br>
&gt; Deleting files from new pg_multixact/members=C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 ok<br>
&gt; Deleting files from new pg_multixact/offsets=C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 ok<br>
&gt; Converting pg_multixact files=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0<br>
&gt; could not open file &quot;/home/heikki/pgsql.93stable/data/pg_multixac=
t/offsets/0000&quot;: No such file or directory<br>
&gt; Failure, exiting<br>
<br>
I don&#39;t think we need to support that case. I hope there are no cluster=
s <br>
in that state still in the wild, and you can work around it by upgrading <b=
r>
to 9.3.5 or above and letting autovacuum run. But I wonder if a <br>
pre-upgrade check with a better error message would still be worthwhile.<br=
>
<br>
<br>
Ashutosh, you were interested in reviewing this earlier. Would you have <br=
>
a chance to review this now, before I commit it? Alexander, Alvaro, <br>
would you have a chance to take a final look too, please?<br>
<br>
- Heikki<br>
</blockquote></div>

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