Re: Avoid multiple calls to memcpy (src/backend/access/index/genam.c)

Hi.

Em qua., 25 de mar. de 2026 às 08:26, lakshmi <lakshmigcdac(at)gmail(dot)com>
escreveu:

>
> Hi,
>>>
>>> Thanks for the suggestion and for the earlier discussion.
>>>
>> Could you repeat the tests without enable-debug?
>>
> I repeated the tests using a non-debug (optimized) build of PostgreSQL
> (19devel), built without --enable-debug.
>
> Test setup:
>
> -
>
> Debian Linux (x86_64)
> -
>
> gcc 12.2.0
> -
>
> AMD Ryzen 5 7535U (6 cores / 12 threads)
> -
>
> pgbench scale factor 1
> -
>
> command: pgbench -p 55432 -d postgres -c 10 -j 4 -T 60 I ran multiple
> iterations for both the original and patched versions and considered the
> stable runs (excluding those affected by checkpoints).
>
> Thanks.

>
> -
>
> Results:
>
> Original:
> TPS: ~1047
> Latency: ~9.5 ms
>
> Patched:
> TPS: ~1040
> Latency: ~9.6 ms
>
> From these runs, the results are quite close, and I didn’t observe a
> consistent performance improvement with the patch under this workload. The
> differences appear to be within normal run-to-run variation.
>
> I agree.

> -
>
> It may be that this change has limited impact in typical cases where
> the number of keys is small. It would be interesting to see how it behaves
> with workloads involving larger numbers of keys or different access
> patterns.
>
> I believe it's unnecessary; I think it's been clearly demonstrated that
there has been no improvement, so it's not worth it.

> -
>
> Please let me know if you’d like me to try any additional scenarios.
>
> Thank you for testing.

For me, the lesson here is that this is the first time I've seen that
unloop doesn't work any better.

best regards,
Ranier Vilela