Re: pgsql: postgres_fdw: Inherit the local transaction's access/deferrable

On Tue, Jun 3, 2025 at 6:45 AM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> No, this is a fix, not a feature, as discussed in the thread; as
> mentioned in the commit message, the previous version of postgres_fdw
> could cause surprising behaviors that would never happen in normal
> cases where a read-only and/or deferrable transaction only
> accesses/modifies data on the local server, so this commit fixes those
> behaviors.  But yes, it makes a behavior change, so I think it’s a
> good idea to add a note about that to the v18 release notes, as
> proposed by Fujii-san.

Sometimes, people can have different opinions about whether something
is a bug fix or a behavior change. So far, I don't think you've
convinced a single person either on the original thread or on this one
that this is a bug fix, so I believe that, at present, the consensus
is that this is a new feature. Although you may not agree with that
consensus, and you may even be right, we all have to do what most
people agree is right rather than what we ourselves prefer.

For what it's worth, I agree with others that this is not just a bug
fix: it's a behavior change that should be subject to the feature
freeze. I personally think that it's probably a desirable behavior
change, and that it's small enough that we could consider leaving it
in v18 if that meets with general approval. We have had cases like
this, where something feels too disruptive to back-patch, but is still
on some level a fix or correction of behavior, in the past, and we
have sometimes decided to handle those by allowing them to be added to
the major release after the feature freeze deadline, but not
back-patching them. So in my mind that is a possibility here.

However, that would require a pretty unanimous agreement that this
change is an improvement, and it appears to me that we don't have
that. I read Fujii Masao's comments to indicate that he doesn't
necessarily agree with the change and wants it reverted, and I read
Michael Paquier's comments the same way. Unless I'm misunderstanding
their position, this needs to be reverted.

--
Robert Haas
EDB: http://www.enterprisedb.com