Re: Significant Execution Time Difference Between PG13.14 and PG16.4 for Query on information_schema Tables.

Hi All,

I hope you're doing well.

I'm writing to kindly requesting if there is a bug tracker ID or any
reference number associated with this issue, I would appreciate it if you
could share it with me.

Thank you for your time and assistance. Please let me know if there's any
additional information you need from me.

Best regards,

Nikhil

On Fri, 30 Aug, 2024, 2:23 am Tom Lane, <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > On Thu, Aug 29, 2024 at 4:47 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> In the meantime, I think this test case is mighty artificial,
> >> and it wouldn't bother me any to just take it out again for the
> >> time being.
>
> > Yeah, I think we can remove the 't1.two+t2.two' test case if we go
> > with your proposed patch to address this performance regression.
>
> Here's a polished-up patchset for that. I made the memoize test
> removal a separate patch because (a) it only applies to master
> and (b) it seems worth calling out as something we might be able
> to revert later.
>
> I found one bug in the draft patch: add_nulling_relids only processes
> Vars of level zero, so we have to apply it before not after adjusting
> the Vars' levelsup. An alternative could be to add a levelsup
> parameter to add_nulling_relids, but that seemed like unnecessary
> complication.
>
> regards, tom lane
>
>