Re: Introduce XID age and inactive timeout based replication slot invalidation

On Thu, Apr 4, 2024 at 5:53 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Thu, Apr 4, 2024 at 4:35 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > > Thanks for the changes. v34-0001 LGTM.
> >
> > I was doing a final review before pushing 0001 and found that
> > 'inactive_since' could be set twice during startup after promotion,
> > once while restoring slots and then via ShutDownSlotSync(). The reason
> > is that ShutDownSlotSync() will be invoked in normal startup on
> > primary though it won't do anything apart from setting inactive_since
> > if we have synced slots. I think you need to check 'StandbyMode' in
> > update_synced_slots_inactive_since() and return if the same is not
> > set. We can't use 'InRecovery' flag as that will be set even during
> > crash recovery.
> >
> > Can you please test this once unless you don't agree with the above theory?
>
> Nice catch. I've verified that update_synced_slots_inactive_since is
> called even for normal server startups/crash recovery. I've added a
> check to exit if the StandbyMode isn't set.
>
> Please find the attached v35 patch.

Thanks for the patch. Tested it , works well. Few cosmetic changes needed:

in 040 test file:
1)
# Capture the inactive_since of the slot from the primary. Note that the slot
# will be inactive since the corresponding subscription is disabled..

2 .. at the end. Replace with one.

2)
# Synced slot on the standby must get its own inactive_since.

. not needed in single line comment (to be consistent with
neighbouring comments)

3)
update_synced_slots_inactive_since():

if (!StandbyMode)
return;

It will be good to add comments here.

thanks
Shveta