Re: Fix unsigned output for signed values in SLRU error reporting

пн, 21 мар. 2022 г. в 16:11, Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com>:

> Afaics offset etc can't be negative, so I don't think this really improves
>> matters. I think there's quite a few other places where we use %u to print
>> integers that we know aren't negative.
>>
>> If anything I think we should change the signed integers to unsigned
>> ones. It
>> might be worth doing that as part of
>>
>> https://www.postgresql.org/message-id/CAJ7c6TPDOYBYrnCAeyndkBktO0WG2xSdYduTF0nxq%2BvfkmTF5Q%40mail.gmail.com
>
>
> That was one of my intentions in the mentioned patch, but I couldn't
> confirm that the page number (and offset) in SLRU was used signed not by
> purpose. Thank you for confirming this. I will try to replace int to
> unsigned where it is relevant in SLRU as part of the mentioned thread.
> Though it could be a big change worth a separate patch maybe.
>
> In the patchset where we're working on making SLRU 64bit [1] we have come
to agreement that:
- signed to unsigned change in SLRU *page* numbering is not needed as
maximum SLRU page number is guaranteed to be much more than 2 times less
than maximum 64-bit XID.
- change of *offset* from int format to the wider one is not needed at all
as multiple of SLRU_PAGES_PER_SEGMENT
and CLOG_XACTS_PER_PAGE (and similar for commit_ts and mxact) is far less
than 2^32 [2]

So the change to printing offset as signed, from this thread, is not going
to be included into SLRU 64-bit thread [1].
It's true that offset can not be negative, but printing int value as %u
isn't nice even if it is not supposed to be negative. So I'd propose the
small patch in this thread be applied separately if none has anything
against it.

[1]
https://www.postgresql.org/message-id/CALT9ZEEf1uywYN%2BVaRuSwNMGE5%3DeFOy7ZTwtP2g%2BW9oJDszqQw%40mail.gmail.com
[2]
https://www.postgresql.org/message-id/20220325.120718.758699124869814269.horikyota.ntt%40gmail.com

--
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>