Horton

Re: BUG #18536: Using WITH inside WITH RECURSIVE triggers a "shouldn't happen" error

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: exclusion@gmail.com
Cc: pgsql-bugs@lists.postgresql.org
Date: 2024-07-14T17:30:55Z
Lists: pgsql-bugs

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I wrote:
> Hmm, that is probably too strong: it will break some queries we've
> historically accepted.  What we need is just to forbid self-references
> within the WITH clause.  The code actually does that already, it's
> just doing it too late; so we can fix this with a simple re-ordering
> of the error checks, as attached.

Oh ...

regression=# WITH RECURSIVE x(n) AS (
select 0 union select 1 order by (select n from x)) select * from x;
ERROR:  missing recursive reference

We have to move *all* of those subsidiary-clause checks to before
the tests of the UNION proper.

			regards, tom lane

Commits

  1. Avoid unhelpful internal error for incorrect recursive-WITH queries.