Re: Time delayed LR (WAS Re: logical replication restrictions)

At Mon, 30 Jan 2023 11:56:33 +0530, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote in
> On Mon, Jan 30, 2023 at 9:43 AM Kyotaro Horiguchi
> <horikyota(dot)ntt(at)gmail(dot)com> wrote:
> >
> > At Mon, 30 Jan 2023 08:51:05 +0530, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote in
> > > On Mon, Jan 30, 2023 at 8:32 AM Kyotaro Horiguchi
> > > <horikyota(dot)ntt(at)gmail(dot)com> wrote:
> > > >
> > > > At Sat, 28 Jan 2023 04:28:29 +0000, "Takamichi Osumi (Fujitsu)" <osumi(dot)takamichi(at)fujitsu(dot)com> wrote in
> > > > > On Friday, January 27, 2023 8:00 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > > > > So, you have changed min_apply_delay from int64 to int32, but you haven't
> > > > > > mentioned the reason for the same? We use 'int' for the similar parameter
> > > > > > recovery_min_apply_delay, so, ideally, it makes sense but still better to tell your
> > > > > > reason explicitly.
> > > > > Yes. It's because I thought I need to make this feature consistent with the recovery_min_apply_delay.
> > > > > This feature handles the range same as the recovery_min_apply delay from 0 to INT_MAX now
> > > > > so should be adjusted to match it.
> > > >
> > > > INT_MAX can stick out of int32 on some platforms. (I'm not sure where
> > > > that actually happens, though.) We can use PG_INT32_MAX instead.
> > > >
> > >
> > > But in other integer GUCs including recovery_min_apply_delay, we use
> > > INT_MAX, so not sure if it is a good idea to do something different
> > > here.
> >
> > The GUC is not stored in a catalog, but.. oh... it is multiplied by
> > 1000.
>
> Which part of the patch you are referring to here? Isn't the check in

Where recovery_min_apply_delay is used. It is allowed to be set up to
INT_MAX but it is used as:

> delayUntil = TimestampTzPlusMilliseconds(xtime, recovery_min_apply_delay);

Where the macro is defined as:

> #define TimestampTzPlusMilliseconds(tz,ms) ((tz) + ((ms) * (int64) 1000))

Which can lead to overflow, which is practically harmless.

> the function defGetMinApplyDelay() sufficient to ensure that the
> 'delay' value stored in the catalog will always be lesser than
> INT_MAX?

I'm concerned about cases where INT_MAX is wider than int32. If we
don't assume such cases, I'm fine with INT_MAX there.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center