Re: API stability [was: pgsql: Fix possible recovery trouble if TRUNCATE overlaps a checkpoint.]

On Tue, Apr 05, 2022 at 03:16:20PM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Tue, Apr 5, 2022 at 10:32 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> My point is that we want that to happen in HEAD, but it's not okay
>>> for it to happen in a minor release of a stable branch.
>
>> I understand, but I am not sure that I agree. I think that if an
>> extension stops compiling against a back-branch, someone will notice
>> the next time they try to compile it and will fix it. Maybe that's not
>> amazing, but I don't think it's a huge deal either.

I agree with Tom's argument. The internals of this structure should
not have changed in a stable branch.

> Well, perhaps it's not the end of the world, but it's still a large
> PITA for the maintainer of such an extension. They can't "just fix it"
> because some percentage of their userbase will still need to compile
> against older minor releases. Nor have you provided any way to handle
> that requirement via conditional compilation.

For example, I recall that some external extensions make use of
sizeof(PGPROC) for their own business. Isn't 412ad7a going to be a
problem to change this structure's internals for already-compiled code
on stable branches?
--
Michael