Horton

Re: Consistently use the XLogRecPtrIsInvalid() macro

Álvaro Herrera <alvherre@kurilemu.de>

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From: Álvaro Herrera <alvherre@kurilemu.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Michael Paquier <michael@paquier.xyz>, Heikki Linnakangas <hlinnaka@iki.fi>, Quan Zongliang <quanzongliang@yeah.net>, pgsql-hackers@lists.postgresql.org
Date: 2025-11-19T16:49:42Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Replace literal 0 with InvalidXLogRecPtr for XLogRecPtr assignments

  2. Replace pointer comparisons and assignments to literal zero with NULL

  3. Use XLogRecPtrIsValid() in various places

  4. Introduce XLogRecPtrIsValid()

On 2025-Nov-19, Robert Haas wrote:

> On Thu, Nov 6, 2025 at 2:48 PM Álvaro Herrera <alvherre@kurilemu.de> wrote:
> > Okay, thanks, I have applied that one to all stable branches, except
> > I didn't add the judgemental comment about XLogRecPtrIsInvalid().
> 
> I'm rather late to the party here, but for what it's worth, I don't
> really think this was a good idea. Anyone who wants to write
> out-of-core code that works in the back-branches must still write it
> the old way, or it will potentially fail on older minor releases.

No, they don't need to.  Thus far, they can still keep their code the
way it is.  The next patch in the series (not yet committed, but I
intend to get it out at some point, unless there are objections) is
going to add an obsolescence warning when their code is compiled with
Postgres 21 -- by which time the minors without the new macro are going
to be two years old.  Nobody needs to compile their code with minor
releases that old.  So they can fix their code to work with Postgres 21
and with all contemporary minors.  They don't need to ensure that their
code compiles with minors older than that.

We could make that Postgres 22, but I don't think that makes any
practical difference.


Maybe you misunderstood what the patch is doing.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/