Re: BUG #18261: Inconsistent results of SELECT affected by joined subqueries

On Mon, Jan 8, 2024, 13:51 Richard Guo <guofenglinux(at)gmail(dot)com> wrote:

>
> On Fri, Jan 5, 2024 at 11:32 AM Andrei Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>
> wrote:
>
>> The regression test shows where two fully equal join clauses, applied on
>> different join levels, differ by the only required_relids. It covers the
>> problem and can be helpful by itself. IMO, one line in this test is
>> redundant (see attachment).
>
>
> Hmm, I don't think the insert statement in the test case is redundant.
> It's needed to verify that the query in the test case gives the correct
> result. Without the insert statement, the wrong plan would give the
> same result as the correct plan, i.e., an empty set in this case.
>
> IMO, if we make some code changes and add a test case for that, we need
> to ensure the test can give a different (and correct of course) result
> than what came before.
>

Thank you for pointing this. Yes, veryfying query result not just plan is
strengthening the test. I'll recheck this and push the fix later today.

------
Regards,
Alexander Korotkov

>