On Wed, 21 Jun 2023 at 00:32, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Japin Li <japinli@hotmail.com> writes:
>> Yeah, SearchSysCache1() need in an transaction block, here is a patch
>> fixed it.
>
> I'm not sure if anyone out there is expecting that this case should
> work, but it probably did work at one time. Rather than throwing
> an error, it'd be better to fix plancache.c so it doesn't fail.
> I looked at the code and found that that's pretty much a one-line
> fix, because there are already code paths that avoid doing anything
> extra for transaction control commands (e.g ROLLBACK, which'd
> otherwise have this same issue).
Agreed, it's much better than throwing an error. LGTM.
>> Another question, why should we need to create a plan cache entry for
>> empty input?
>
> Well, we have to have something to support the wire protocol behavior
> for this case. No doubt we could hack up postgres.c to handle it
> without a plan cache entry, but it'd be far more invasive to do it
> there.
>
Thanks for your explanation! Got it.
--
Regrads,
Japin Li.
