Re: split TOAST support out of postgres.h

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Tue, Jan 10, 2023 at 3:48 AM Peter Eisentraut
> <peter(dot)eisentraut(at)enterprisedb(dot)com> wrote:
>>> SET_VARSIZE alone appears in 74 pgxn distributions, so I predict extension
>>> breakage en masse. I would revert this.

>> Well, that was sort of my thinking, but people seemed to like this. I'm
>> happy to consider alternatives.

> I don't think it would be very nice to do something like this in a
> minor release. But in a new major release, I think it's fine. I've
> been on the hook to maintain extensions in the face of these kinds of
> changes at various times over the years, and it's never taken me much
> time.

Yeah, that was my thinking. We could never do any header refactoring
at all if the standard is "will some extension author need to add a #if".
In practice, we make bigger adjustments than this all the time,
both in header layout and in individual function APIs.

Now, there is a fair question whether splitting this code out of
postgres.h is worth any trouble at all. TBH my initial reaction
had been "no". But once we found that only 40-ish backend files
need to read this new header, I became a "yes" vote because it
seems clear that there will be a total-compilation-time benefit.

regards, tom lane