Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> On Tue, Feb 7, 2023 at 2:12 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I don't see any change in this query plan when I remove that code, so
>> I'm not sure you're explaining your point very well.
> To observe an obvious plan change, we can add unique constraint for 'a'
> and look how outer-join removal works.
Ah. Yeah, that's pretty convincing, especially since v15 manages to
find that optimization. Pushed with a test case.
regards, tom lane