From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: Fujii Masao <masao.fujii@oss.nttdata.com>,
        Amit Kapila <amit.kapila16@gmail.com>,
        Laurenz Albe <laurenz.albe@cybertec.at>,
        Nisha Moond <nisha.moond412@gmail.com>,
        Gunnar Morling <gunnar.morling@googlemail.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: Unexpected behavior when setting "idle_replication_slot_timeout"
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Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Sat, 05 Jul 2025 08:10:10 -0700"
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Date: Sat, 05 Jul 2025 11:56:48 -0400
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Saturday, July 5, 2025, Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
>> Do you see any serious downside to switching the unit to seconds? I don't
>> think it introduces any serious issues. On the contrary, it gives users
>> finer
>> control over the timeout, and additionally works around the issue
>> that we're discussing here.

> I do not, and would rather we make the change.  Minutes are an
> unconventional base unit for time in our world and should be avoided.

By my count, there are ten GUCs declared with GUC_UNIT_S and three
with GUC_UNIT_MIN.  I'd say that there may be some lean towards
seconds but David's argument seems like pure hyperbole.

I'm kind of down on changing the unit, because it will *silently*
break configuration files where the value was set without a unit.

May I suggest an alternative?  We could change the variable from int
to float type and continue to specify it in minutes.  That will have
exactly zero compatibility impact, it allows sub-minute values to
be selected at need, and it removes the need for hair-splitting
documentation about what the rounding rules are.

We previously did the same with vacuum_cost_delay to avoid worries
about how to specify sub-millisecond precision for that.  So the
infrastructure is already in place, I think.  The patch will be
different from what is proposed but should need to touch pretty
much the same places.

			regards, tom lane