From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: lxndrkrlv@gmail.com <lxndrkrlv@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17233: Incorrect behavior of DELETE command with bad subquery in WHERE clause
Date: Thu, 18 Aug 2022 22:07:02 -0400
Message-ID: <Yv7wRmKX01Q2gfPo@momjian.us> (raw)
In-Reply-To: <2792105.1660859528@sss.pgh.pa.us>
References: <17233-afb9d806aaa64b17@postgresql.org>
<CAKFQuwbnETbhnBYtMA8HNJwf0ipwAETd58=K0JzPs22Of2ZhcA@mail.gmail.com>
<1409812.1634481258@sss.pgh.pa.us>
<Yv6xeki829pitIXd@momjian.us>
<2792105.1660859528@sss.pgh.pa.us>
On Thu, Aug 18, 2022 at 05:52:08PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > Feedback?
>
> > -- test some error cases where LATERAL should have been used but wasn't
> > select f1,g from int4_tbl a, (select f1 as g) ss;
> > ERROR: column "f1" does not exist
> > LINE 1: select f1,g from int4_tbl a, (select f1 as g) ss;
> > ^
> > -HINT: There is a column named "f1" in table "a", but it cannot be referenced from this part of the query.
> > +HINT: There is a column named "f1" in table "a" and another table so a table-qualified column reference is required.
>
> That one has gone from accurate to completely wrong. First, it's not
> the case that there's more than one possible referent, and second,
> table-qualifying the reference wouldn't help. What *would* help here
> is adding LATERAL, but I'm not sure if we can easily tell whether that
> is the case.
My error text was written based on the email report and was just a test
to see what queries trigger it.
> I think perhaps the existing message is mislabeled: it's not a hint
> as written, but errdetail, because it's entirely factual. For this
> particular example, what would be on-point is
>
> DETAIL: There is a column named "f1" in table "a", but it cannot be referenced from this part of the query.
> HINT: To reference that column, you must mark this subquery with LATERAL.
Yes, the problem is that I don't think we want to just be making a
suggestion when we have other cases where LATERAL would not help.
> While we don't insist that hints be 100% accurate, it's not good
> if they're wildly unhelpful. So I'm not sure if we can determine
> whether or not it's likely to be on-point.
>
> I didn't look too closely at your other examples.
Yeah, I think someone will have to have a new idea to improve this.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com
Indecision is a decision. Inaction is an action. Mark Batterson
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Cc: bruce@momjian.us, tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, lxndrkrlv@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17233: Incorrect behavior of DELETE command with bad subquery in WHERE clause
In-Reply-To: <Yv7wRmKX01Q2gfPo@momjian.us>
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