From: Eric Ridge <eebbrr@gmail.com>
Message-Id: <9A42D802-5994-4DAF-86FB-AB5954840216@gmail.com>
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Subject: Re: pg18 bug? SELECT query doesn't work
Date: Tue, 6 Jan 2026 13:10:40 -0500
In-Reply-To: <CAKFQuwZS4dO2xJeL7yT-D20J-WR15rCPE9iXta8F9WuFHvxXTA@mail.gmail.com>
Cc: pgsql-general <pgsql-general@postgresql.org>
To: "David G. Johnston" <david.g.johnston@gmail.com>
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> On Jan 6, 2026, at 12:00=E2=80=AFPM, David G. Johnston =
<david.g.johnston@gmail.com> wrote:
>=20
> While I haven't dug into the actual specifics of this report in =
detail, the change in question happened back in v10.
>=20
> https://www.postgresql.org/docs/10/release-10.html

Thanks.  I wouldn't have thought to look back that far since the query =
worked on v15.  Interesting.

> The failure to emit an error when it probably should have is likely a =
bug in older versions since fixed.

Fair enough.

> That the behavior depends on the chosen plan and plans differ when you =
do and do not materialize a CTE is likewise not surprising.=20

I guess I wouldn't expect Postgres to generate a plan that it then can't =
execute.  That's what's surprising to me.

But it's fine.  In all my years of using Postgres this is the first time =
I've run into a query that no longer executes, so I wanted to bring it =
to y'alls attention.

Thanks again!

eric=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: =
after-white-space;"><div><blockquote type=3D"cite"><div>On Jan 6, 2026, =
at 12:00=E2=80=AFPM, David G. Johnston =
&lt;david.g.johnston@gmail.com&gt; wrote:</div><div><div dir=3D"ltr" =
style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
18px; font-style: normal; font-variant-caps: normal; font-weight: 400; =
letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; text-decoration: none;"><div =
dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family: arial, =
helvetica, sans-serif;"><br></div></div><div class=3D"gmail_quote =
gmail_quote_container"><div class=3D"gmail_default" style=3D"font-family: =
arial, helvetica, sans-serif;">While I haven't dug into the actual =
specifics of this report in detail, the change in question happened back =
in v10.</div><div class=3D"gmail_default" style=3D"font-family: arial, =
helvetica, sans-serif;"><br></div><div class=3D"gmail_default" =
style=3D"font-family: arial, helvetica, sans-serif;"><a =
href=3D"https://www.postgresql.org/docs/10/release-10.html">https://www.po=
stgresql.org/docs/10/release-10.html</a></div></div></div></div></blockquo=
te><div><br></div>Thanks. &nbsp;I wouldn't have thought to look back =
that far since the query worked on v15. =
&nbsp;Interesting.</div><div><br><blockquote type=3D"cite"><div =
dir=3D"ltr" style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; =
font-size: 18px; font-style: normal; font-variant-caps: normal; =
font-weight: 400; letter-spacing: normal; text-align: start; =
text-indent: 0px; text-transform: none; white-space: normal; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: =
none;"><div class=3D"gmail_quote gmail_quote_container"><div =
class=3D"gmail_default" style=3D"font-family: arial, helvetica, =
sans-serif;">The failure to emit an error when it probably should have =
is likely a bug in older versions since =
fixed.</div></div></div></blockquote><div><br></div><div>Fair =
enough.</div><div><br></div><blockquote type=3D"cite"><div dir=3D"ltr" =
style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
18px; font-style: normal; font-variant-caps: normal; font-weight: 400; =
letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; text-decoration: none;"><div =
class=3D"gmail_quote gmail_quote_container"><div class=3D"gmail_default" =
style=3D"font-family: arial, helvetica, sans-serif;">That the behavior =
depends on the chosen plan and plans differ when you do and do not =
materialize a CTE is likewise not surprising.&nbsp; =
</div></div></div></blockquote><div><br></div><div>I guess I wouldn't =
expect Postgres to generate a plan that it then can't execute. =
&nbsp;That's what's surprising to me.</div><div><br></div><div>But it's =
fine. &nbsp;In all my years of using Postgres this is the first time =
I've run into a query that no longer executes, so I wanted to bring it =
to y'alls attention.</div><div><br></div><div>Thanks =
again!</div><div><br></div><div>eric</div></div></body></html>=

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