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From: =?UTF-8?Q?H=C3=BCseyin_Demir?= <huseyin.d3r@gmail.com>
Date: Mon, 9 Feb 2026 18:16:26 +0100
Message-ID: <CAB5wL7ay2WNdAJZLoDngou=qa4y=uKkQhLZbNVg8kcduwkYqpQ@mail.gmail.com>
Subject: Re: BUG #19393: pg_upgrade fails with duplicate key violation when
 CHECK constraint named *_not_null exists
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: pgsql-bugs@lists.postgresql.org
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Hi,

> I would prefer not to, but I don't have a strong opinion about it.
> Which name PostgreSQL chooses for the generated NOT NULL constraint
> is not important, as long as it doesn't conflict with the existing name.

I also agree that it solves the problem in 18 which I already tested.
Thanks again for your help.


Laurenz Albe <laurenz.albe@cybertec.at>, 9 =C5=9Eub 2026 Pzt, 12:01 tarihin=
de
=C5=9Funu yazd=C4=B1:

> On Mon, 2026-02-09 at 07:24 +0100, H=C3=BCseyin Demir wrote:
> > Thanks for the patch and LGTM for PostgreSQL 18.
>
> Thanks for checking!
>
> > I tried to create following table on PG18
> >
> > benchmark=3D# CREATE TABLE two_not_null_constraints (
> >      col integer NOT NULL,
> >      CONSTRAINT two_not_null_constraints_col_not_null CHECK (col IS NOT
> NULL)
> >   );
> > ERROR:  duplicate key value violates unique constraint
> "pg_constraint_conrelid_contypid_conname_index"
> > DETAIL:  Key (conrelid, contypid, conname)=3D(16385, 0,
> two_not_null_constraints_col_not_null) already exists.
> >
> > In PG17 I was able to create the table.
>
> Yes, because what causes your problemm is a new feature in v18.
>
> > One question during the tests should we confirm the output of
> pg_constraint table ?
> > It would make sense during the tests but the current test is also good
> to proceed.
>
>
>
> Yours,
> Laurenz Albe
>

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<div dir=3D"ltr"><div>Hi,=C2=A0</div><div><br></div><div>&gt; I would prefe=
r not to, but I don&#39;t have a strong opinion about it.<br>&gt; Which nam=
e PostgreSQL chooses for the generated NOT NULL constraint<br>&gt; is not i=
mportant, as long as it doesn&#39;t conflict with the existing name.</div><=
div><br></div><div>I also agree that it solves the problem in 18 which I al=
ready tested.=C2=A0</div><div>Thanks again for your help.</div><div><br></d=
iv><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr" cl=
ass=3D"gmail_attr">Laurenz Albe &lt;<a href=3D"mailto:laurenz.albe@cybertec=
.at">laurenz.albe@cybertec.at</a>&gt;, 9 =C5=9Eub 2026 Pzt, 12:01 tarihinde=
 =C5=9Funu yazd=C4=B1:<br></div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-lef=
t:1ex">On Mon, 2026-02-09 at 07:24 +0100, H=C3=BCseyin Demir wrote:<br>
&gt; Thanks for the patch and LGTM for PostgreSQL 18.<br>
<br>
Thanks for checking!<br>
<br>
&gt; I tried to create following table on PG18<br>
&gt; <br>
&gt; benchmark=3D# CREATE TABLE two_not_null_constraints (<br>
&gt; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0col integer NOT NULL,<br>
&gt; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0CONSTRAINT two_not_null_constraints_col_=
not_null CHECK (col IS NOT NULL)<br>
&gt; =C2=A0=C2=A0);<br>
&gt; ERROR:=C2=A0 duplicate key value violates unique constraint &quot;pg_c=
onstraint_conrelid_contypid_conname_index&quot;<br>
&gt; DETAIL:=C2=A0 Key (conrelid, contypid, conname)=3D(16385, 0, two_not_n=
ull_constraints_col_not_null) already exists.<br>
&gt; <br>
&gt; In PG17 I was able to create the table.<br>
<br>
Yes, because what causes your problemm is a new feature in v18.<br>
<br>
&gt; One question during the tests should we confirm the output of pg_const=
raint table ?<br>
&gt; It would make sense during the tests but the current test is also good=
 to proceed.<br>
<br><br>
<br>
Yours,<br>
Laurenz Albe<br>
</blockquote></div></div>

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