Re: persist logical slots to disk during shutdown checkpoint

On Fri, 1 Sept 2023 at 10:06, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Thu, Aug 31, 2023 at 6:12 PM Ashutosh Bapat
> <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
> >
> > On Thu, Aug 31, 2023 at 2:52 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > All but one. Normally, the idea of marking dirty is to indicate that
> > > we will actually write/flush the contents at a later point (except
> > > when required for correctness) as even indicated in the comments atop
> > > ReplicatioinSlotMarkDirty(). However, I see your point that we use
> > > that protocol at all the current places including CreateSlotOnDisk().
> > > So, we can probably do it here as well.
> >
> > yes
> >
>
> I think we should also ensure that slots are not invalidated
> (slot.data.invalidated != RS_INVAL_NONE) before marking them dirty
> because we don't allow decoding from such slots, so we shouldn't
> include those.

Added this check.

Apart from this I have also fixed the following issues that were
agreed on: a) Setting slots to dirty in CheckPointReplicationSlots
instead of setting it in SaveSlotToPath b) The comments were moved
from ReplicationSlot and moved to CheckPointReplicationSlots c) Tests
will be run in autovacuum = off d) updating last_saved_confirmed_flush
based on cp.slotdata.confirmed_flush rather than
slot->data.confirmed_flush.
I have also added the commitfest entry for this at [1].

Thanks to Ashutosh/Amit for the feedback.
Attached v7 version patch has the changes for the same.
[1] - https://commitfest.postgresql.org/44/4536/

Regards,
Vignesh