Re: pgsql: Fix more holes with SLRU code in need of int64 for segment numbe

On 07.08.24 17:53, Alexander Korotkov wrote:
> On Wed, Aug 7, 2024 at 12:07 PM Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>> On 27.07.24 00:24, Michael Paquier wrote:
>>> Fix more holes with SLRU code in need of int64 for segment numbers
>>>
>>> This is a continuation of 3937cadfd438, taking care of more areas I have
>>> managed to miss previously.
>>>
>>> Reported-by: Noah Misch
>>> Reviewed-by: Noah Misch
>>> Discussion: https://postgr.es/m/20240724130059.1f.nmisch@google.com
>>> Backpatch-through: 17
>>>
>>> Branch
>>> ------
>>> master
>>>
>>> Details
>>> -------
>>> https://git.postgresql.org/pg/commitdiff/c9e24573905bef7fc3e4efb02bdb4d0cc8e43c51
>>
>> I don't understand this patch. The previous patches that this
>> references changed various variables to int64 and made adjustments
>> following from that. But this patch takes variables and function
>> results that are of type int and casts them to unsigned long long before
>> printing. I don't see what that accomplishes, and it's not clear based
>> on just the explanation that this is a continuation of a previous patch
>> that doesn't do that. Is there a plan to change these things to int64
>> as well at some point?
>
> There is a plan indeed. The patchset [1] should include conversion
> multixacts to 64-bit (It surely included that in earlier versions, I
> didn't look the last versions though). I doubt this will be ready for
> v18. So this commit might be quite preliminary. But I would prefer
> to leave it there as soon as it has already landed. Opinions?

I think you should change the output formats at the same time as you
change the variable types. That way the compiler can cross-check this.
Otherwise, if you later forget to change a variable, these casts will
hide it. Or if the future patches turn out differently, then we have
this useless code.

> Links.
> 1. https://www.postgresql.org/message-id/CAJ7c6TND0bCnwU1SmxTsFewK4XJGBep343vf%2BT%2BGQ-a5S5hC0w%40mail.gmail.com

It looks like the commit I'm talking about here is a subset of v55-0001
from that thread? So why is some of this being committed now into v17?
But as I wrote above, I think this approach is a bad idea.