Re: Reuse child_relids in try_partitionwise_join was Re: Assert failure on bms_equal(child_joinrel->relids, child_joinrelids) - Mailing list pgsql-hackers

On Mon, Jun 10, 2024 at 8:15 AM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Mon, Jun 10, 2024 at 3:09 AM Ashutosh Bapat
> <ashutosh.bapat.oss@gmail.com> wrote:
> > This is just one instance of measurements. If I run the experiment multiple times the results and the patterns will
vary.Usually I have found planning time to vary within 5% for regular tables and within 9% for partitioned tables with
alarge number of partitions. Below are measurements with the experiment repeated multiple times. For a given number of
partitionedtables (each with 1000 partitions) being joined, planning time is measured 10 consecutive times. For this
setof 10 runs we calculate average and standard deviation of planning time. Such 10 sets are sampled. This means
planningtime is sampled 100 times in total with and without patch respectively. Measurements with master and patched
arereported in the attached excel sheet. 
>
> Well, this is fine then I guess, but if the original results weren't
> stable enough for people to draw conclusions from, then it's better
> not to post them, and instead do this work to get results that are
> stable before posting.

Just doing a quick code review of the structure and the caller, I'd
agree that this is properly hoisting the invariant, so don't see that
it should contribute to any performance regressions.  To the extent
that it's called multiple times I can see that it's an improvement,
with minimal code shuffling it seems like a sensible change (even in
the single-caller case).

In short +1 from me.

David