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From: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Date: Thu, 2 Jul 2026 18:46:41 +0530
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 <CAJTYsWXij=ZzKDqVMTyGR7=Suf5CJfezBYHyf7+2GWk_CPpUVw@mail.gmail.com>
Subject: Re: Document COPY FROM WHERE restrictions on generated and system
 columns
To: Fujii Masao <masao.fujii@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
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Hi,

On Thu, 2 Jul 2026 at 18:41, Fujii Masao <masao.fujii@gmail.com> wrote:

> Hi,
>
> I found that generated columns and system columns cannot be used in
> COPY FROM WHERE expressions, but the COPY docs still mentions
> only the restriction on subqueries.
>
> So I've created the attached patch which updates the docs to also list
> generated columns and system columns as unsupported in COPY FROM WHERE
> expressions.
>
> Since generated columns have been rejected in COPY FROM WHERE since
> v13, that docs change should be backpatched to all supported branches.
> But the system-column restriction was introduced in v19, so that part
> does not need to be backpatched.
>
> Thoughts?
>

Thanks for the patch!

I think it makes sense to add the system columns and generated
columns limitation to the documentation, patch LGTM.

Regards,
Ayush

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<div dir=3D"ltr"><div dir=3D"ltr">Hi,</div><br><div class=3D"gmail_quote gm=
ail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Thu, 2 Jul 20=
26 at 18:41, Fujii Masao &lt;<a href=3D"mailto:masao.fujii@gmail.com">masao=
.fujii@gmail.com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" =
style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);pa=
dding-left:1ex">Hi,<br>
<br>
I found that generated columns and system columns cannot be used in<br>
COPY FROM WHERE expressions, but the COPY docs still mentions<br>
only the restriction on subqueries.<br>
<br>
So I&#39;ve created the attached patch which updates the docs to also list<=
br>
generated columns and system columns as unsupported in COPY FROM WHERE<br>
expressions.<br>
<br>
Since generated columns have been rejected in COPY FROM WHERE since<br>
v13, that docs change should be backpatched to all supported branches.<br>
But the system-column restriction was introduced in v19, so that part<br>
does not need to be backpatched.<br>
<br>
Thoughts?<br></blockquote><div><br>Thanks for the patch!<br><br>I think it =
makes sense to add the system columns and generated<br>columns limitation t=
o the documentation, patch LGTM.<br><br>Regards,<br>Ayush=C2=A0</div></div>=
</div>

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