Re: Define DatumGetInt8 function.

From: Aleksander Alekseev <aleksander(at)tigerdata(dot)com>
To: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Cc: Peter Eisentraut <peter(at)eisentraut(dot)org>, Kirill Reshke <reshkekirill(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Define DatumGetInt8 function.
Date: 2026-03-13 10:55:44
Message-ID: CAJ7c6TMcGu8qmRe1gZfJ-gOzVnZq-t=fwn-UuyStx1w6ZyydMw@mail.gmail.com
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Hi Peter,

Thanks for your feedback.

> I'm tempted to think the correct direction here would be to use uint8
> and its associated macros and functions more rigorously, not less.

OK, if my understanding is correct this leaves us char_increment() and
char_decrement() which currently use DatumGetUInt8 inconsistently with
CharGetDatum for the argument and return value correspondingly.

> I don't think it's worth making an isolated fix here for the one use of
> UInt8GetDatum()

I think you meant not this particular change so I included it to the
patch. We can keep nbtcompare.c as if you believe this change is not
that important (it arguably isn't).

> The change in pageinspect looks correct, but then when you look
> nearby and further around, you will find that there are also a bunch of
> (if not most) UInt16GetDatum and UInt32GetDatum that are wrong
> [...]

Agree. I did my best to fix all the inconsistencies in pageinsect.

> There are a lot of opportunities to clean this up, and I suspect that
> while many of these will work either way in practice because the actual
> values don't go far enough to hit the signed/unsigned boundary, I think
> there could a number of little bugs here to be fixed.

I believe you were referring to places other than pageinspect. I will
investigate and create separate threads with corresponding patches
later.

--
Best regards,
Aleksander Alekseev

Attachment Content-Type Size
v3-0001-Fix-several-Datum-conversion-inconsistencies.patch text/x-patch 8.9 KB

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