Re: Unexpected behavior when setting "idle_replication_slot_timeout"

On Fri, Jul 4, 2025 at 9:54 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> On 2025/07/05 1:07, Laurenz Albe wrote:
> > On Sat, 2025-07-05 at 00:22 +0900, Fujii Masao wrote:
> >> On 2025/07/04 23:12, Fujii Masao wrote:
> >>> But I wonder why the current unit of this GUC is minutes (GUC_UNIT_MIN).
> >>> Since at least two users (including myself) tried to set it to a value
> >>> less than 1 minute, it might worth considering changing the unit to seconds
> >>> (GUC_UNIT_S). Also which would reduces the chance of the reported trouble.
> >>
> >> Attached patch changes unit of idle_replication_slot_timeout to seconds.
> >
> > -1
> >
> > I think that the reason that several users tried to set it it less than a minute
> > is that they were trying to test the feature and didn't want to wait long.
> > I cannot imagine that anybody will want to abandon a standby server just
> > because it is idle for more than 30 seconds.
>
> Maybe. But changing the unit to seconds doesn't make things worse, does it?
> It still allows users to set values greater than 1 minute, and also less than
> 1 minute for debugging or testing purposes, if needed.
>

We expect the value of this variable to be in hours or, in some cases,
days. Specifying in seconds would be inconvenient for users. Now, I
agree there is a value in testing/debugging to allow it to be seconds,
but the same could be said for other variables whose units are in
minutes, like log_rotation_age and wal_summary_keep_time.

> Or are you suggesting we should disallow values below 1 minute?
>

We should be consistent with other similar GUC variables whose unit is
in GUC_UNIT_MIN.

--
With Regards,
Amit Kapila.