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Date: Wed, 7 Aug 2024 21:52:40 +0200
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Subject: Re: pgsql: Fix more holes with SLRU code in need of int64 for segment
 numbe
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
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From: Peter Eisentraut <peter@eisentraut.org>
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On 07.08.24 17:53, Alexander Korotkov wrote:
> On Wed, Aug 7, 2024 at 12:07 PM Peter Eisentraut <peter@eisentraut.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.