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

On Mon, Jan 8, 2024 at 2:49 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> 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.

Pushed. Thanks again, Richard.

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Regards,
Alexander Korotkov