Re: Options to control remote transactions’ access/deferrable modes in postgres_fdw

On Sun, May 4, 2025 at 9:30 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> As read-only
> subtransactions can’t change to read-write, and a read-only
> main-transaction can’t change to read-write after first snapshot,
> either (note: begin_remote_xact is called after it), all we need to do
> is track the nesting level of the outermost read-only transaction in
> the local transaction and control the access mode of remote
> transactions based on it so that they have the same access mode as the
> local transaction at each subtransaction level, like the attached.

I noticed that an assertion I added to pgfdw_subxact_callback fails
when running some transactions.  To fix, I just removed the assertion.
Attached is an updated version of the patch.  I also added a test case
that was causing the failure, and tweaked some comments/docs a little
bit.

Best regards,
Etsuro Fujita