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

On Tue, 19 Nov 2024 at 12:51, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com> wrote:
>
> On Thu, Nov 14, 2024 at 9:14 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> >
> > On Wed, 13 Nov 2024 at 15:00, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com> wrote:
> > >
> > > Please find the v48 patch attached.
> > >
> > 2) Currently it allows a minimum value of less than 1 second like in
> > milliseconds, I feel we can have some minimum value at least something
> > like checkpoint_timeout:
> > diff --git a/src/backend/utils/misc/guc_tables.c
> > b/src/backend/utils/misc/guc_tables.c
> > index 8a67f01200..367f510118 100644
> > --- a/src/backend/utils/misc/guc_tables.c
> > +++ b/src/backend/utils/misc/guc_tables.c
> > @@ -3028,6 +3028,18 @@ struct config_int ConfigureNamesInt[] =
> > NULL, NULL, NULL
> > },
> >
> > + {
> > + {"replication_slot_inactive_timeout", PGC_SIGHUP,
> > REPLICATION_SENDING,
> > + gettext_noop("Sets the amount of time a
> > replication slot can remain inactive before "
> > + "it will be invalidated."),
> > + NULL,
> > + GUC_UNIT_S
> > + },
> > + &replication_slot_inactive_timeout,
> > + 0, 0, INT_MAX,
> > + NULL, NULL, NULL
> > + },
> >
>
> Currently, the feature is disabled by default when
> replication_slot_inactive_timeout = 0. However, if we set a minimum
> value, the default_val cannot be less than min_val, making it
> impossible to use 0 to disable the feature.
> Thoughts or any suggestions?

We could implement this similarly to how the vacuum_buffer_usage_limit
GUC is handled. Setting the value to 0 would allow the operation to
use any amount of shared_buffers. Otherwise, valid sizes would range
from 128 kB to 16 GB. Similarly, we can modify
check_replication_slot_inactive_timeout to behave in the same way as
check_vacuum_buffer_usage_limit function.

Regards,
Vignesh