Re: tid_blockno() and tid_offset() accessor functions - Mailing list pgsql-hackers

From Ayush Tiwari
Subject Re: tid_blockno() and tid_offset() accessor functions
Date
Msg-id CAJTYsWVt5-R_2j2Wy+i5d-tw67SQ9uGVmd_R+dP-PgsBgGRfkA@mail.gmail.com
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In response to Re: tid_blockno() and tid_offset() accessor functions  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Hi,

Thank you all for the reviews and discussion!

On the strictness question raised by Greg — I agree with Andres here. These functions are meant for inspecting tid values that already exist, so rejecting "impossible" values like (-1,0) would not be providing any real benefit. I believe the tid input function is the appropriate place for any validation, and these assessors should just faithfully report what's in the datum.

Regards,
Ayush

On Mon, 9 Mar 2026 at 19:32, Andres Freund <andres@anarazel.de> wrote:
Hi,

On 2026-03-09 09:34:46 -0400, Greg Sabino Mullane wrote:
> On Sun, Mar 8, 2026 at 3:31 PM Tomas Vondra <tomas@vondra.me> wrote:
>
> > No opinion. For displaying the bogus TID value (like "(-1,0)") it's
> > probably OK to show values that are a bit weird. If anything, we should
> > be more careful on input, it's too late for tid_block() to decide what to
> > do with an "impossible" TID value.
> >
>
> This one doesn't sit right with me. I think it's not too late. No reason
> why tid_block cannot be stricter here than tid itself and complain. Other
> than that, the patch looks good to me.

I don't see any advantage in that. These functions are useful for inspecting
tid values that come from some source. When would you *ever* gain *anything*
from not being able to see the block / offset of a tid datum that you already
have?

This isn't an end user focused type / set of accessor functions were being
particularly careful about input validation will perhaps prevent users from
making mistakes...

Greetings,

Andres Freund

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