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

From: "Takamichi Osumi (Fujitsu)" <osumi(dot)takamichi(at)fujitsu(dot)com>
To: 'shveta malik' <shveta(dot)malik(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>
Cc: vignesh C <vignesh21(at)gmail(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, "dilipbalaut(at)gmail(dot)com" <dilipbalaut(at)gmail(dot)com>, "amit(dot)kapila16(at)gmail(dot)com" <amit(dot)kapila16(at)gmail(dot)com>, "euler(at)eulerto(dot)com" <euler(at)eulerto(dot)com>, "m(dot)melihmutlu(at)gmail(dot)com" <m(dot)melihmutlu(at)gmail(dot)com>, "andres(at)anarazel(dot)de" <andres(at)anarazel(dot)de>, "marcos(at)f10(dot)com(dot)br" <marcos(at)f10(dot)com(dot)br>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: Time delayed LR (WAS Re: logical replication restrictions)
Date: 2023-01-20 18:46:53
Message-ID: TYCPR01MB837363C75D9876B7C1529D06EDC59@TYCPR01MB8373.jpnprd01.prod.outlook.com
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On Friday, January 20, 2023 5:54 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
> On Fri, Jan 20, 2023 at 1:08 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
>
> > a) the message should say that this is the *remaining* time to left to wait.
> >
> > b) it might be convenient to know from the log what was the original
> > min_apply_delay value in the 1st place.
> >
> > For example, the logs might look something like this:
> >
> > DEBUG: time-delayed replication for txid 1234, min_apply_delay =
> > 160000 ms. Remaining wait time: 159972 ms
> > DEBUG: time-delayed replication for txid 1234, min_apply_delay =
> > 160000 ms. Remaining wait time: 142828 ms
> > DEBUG: time-delayed replication for txid 1234, min_apply_delay =
> > 160000 ms. Remaining wait time: 129994 ms
> > DEBUG: time-delayed replication for txid 1234, min_apply_delay =
> > 160000 ms. Remaining wait time: 110001 ms ...
> >
>
> +1
> This will also help when min_apply_delay is set to a new value in between the
> current wait. Lets say, I started with min_apply_delay=5 min, when the worker
> was half way through this, I changed min_apply_delay to 3 min or say 10min, I
> see the impact of that change i.e. new wait-time is adjusted, but log becomes
> confusing. So, please keep this scenario as well in mind while improving
> logging.
Yes, now the change of min_apply_delay value can be detected
since I followed the format provided above. So, this scenario is also covered.

Best Regards,
Takamichi Osumi

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