Re: Avoid unecessary MemSet call (src/backend/utils/cache/relcache.c)

On Tue, Aug 2, 2022 at 3:09 AM Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> wrote:
>
> Em sáb., 16 de jul. de 2022 às 16:54, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> escreveu:
>>
>>
>>
>> Em sáb, 16 de jul de 2022 2:58 AM, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> escreveu:
>>>
>>> On 11.07.22 21:06, Ranier Vilela wrote:
>>> > Em qui., 7 de jul. de 2022 às 14:01, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com
>>> > <mailto:ranier(dot)vf(at)gmail(dot)com>> escreveu:
>>> >
>>> > Attached the v1 of your patch.
>>> > I think that all is safe to switch MemSet by {0}.
>>> >
>>> > Here the rebased patch v2, against latest head.
>>>
>>> I have committed my patch with Álvaro's comments addressed
>>
>> I see.
>> It's annoing that old compiler (gcc 4.7.2) don't handle this style.
>>
>>>
>>> Your patch appears to add in changes that are either arguably out of
>>> scope or would need further review (e.g., changing memset() calls,
>>> changing the scope of some variables, changing places that need to worry
>>> about padding bits). Please submit separate patches for those, and we
>>> can continue the analysis.
>>
>> Sure.
>
> Hi, sorry for the delay.
> Like how https://github.com/postgres/postgres/commit/9fd45870c1436b477264c0c82eb195df52bc0919
> New attempt to remove more MemSet calls, that are safe.
>
> Attached v3 patch.
>
> regards,
> Ranier Vilela

Hi, I have not been closely following this thread, but it's starting
to sound very deja-vu with something I proposed 3 years ago. See [1]
"Make use of C99 designated initialisers for nulls/values arrays".
That started off with lots of support, but then there was a suggestion
that the {0} should be implemented as a macro, and the subsequent
discussions about that macro eventually bikeshedded the patch to
death.

It might be a good idea if you check that old thread so you can avoid
the same pitfalls. I hope you have more luck than I did ;-)

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[1] https://www.postgresql.org/message-id/flat/2793d0d2-c65f-5db0-4f89-251188438391%40gmail.com#102ee1b34a8341f28758efc347874b8a

Kind Regards,
Peter Smith.
Fujitsu Australia