RE: [PATCH] Release replication slot on error in SQL-callable slot functions

On Tuesday, August 4, 2026 7:17 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> On Tue, Aug 4, 2026 at 4:26 PM Zhijie Hou (Fujitsu)
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> >
> > On Tuesday, August 4, 2026 4:39 PM Zhijie Hou (Fujitsu)
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > > On Friday, July 31, 2026 3:12 AM Bharath Rupireddy
> > > <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> > > >
> > > > I read the issue, patches and comments so far and here's my take on it.
> > > >
> > > > ...
> > >
> > > Thanks for sharing the patch.
> > >
> >
> > The only thing I notice is that this new design seems to touch more scope than
> > the original PG_TRY/PG_CATCH approach, since it releases the slot not only on
> > ERROR but also on a manual transaction abort (a direct AbortCurrentTransaction()
> > call without an intervening ERROR). It also seems slightly inconsistent that we
> > do this for subtransactions but not for top-level transactions, but maybe it's
> > OK as it only targets to fix the PL/pgSQL EXCEPTION case.
> >
> > One interesting case I thought of: we currently record
> > GetCurrentSubTransactionId() when creating or acquiring a slot, and that ID is a
> > logical subxid (starting from 1). So it looks possible for the following to
> > happen: the user acquires the slot in a subtransaction with subxid 2 and commits
> > the whole transaction; then, in a new transaction, the user starts a
> > subtransaction that also gets subxid 2 and aborts it.
>
> IIUC, you are referring to the case which Bharath and myself discussed
> in [1]. See [1] and previous few emails.
>
> > In that case the slot
> > would be released, even though the aborted subtransaction is a different one
> > from the subtransaction that originally acquired the slot.
>
> Even if that happens, I think it is covered because on Commit, patch
> changes `acquiredInSubId` to parent-Id and thus a new subxid 2 will
> not be releasing it.

Right, I've confirmed that this can't happen. I'm OK with keeping this code,
since it's future-proof - otherwise, others might raise the same concern I
imagined above.

Best Regards,
Zhijie Hou