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From: Amit Kapila <[email protected]>
To: Kyotaro Horiguchi <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: Time delayed LR (WAS Re: logical replication restrictions)
Date: Thu, 9 Feb 2023 13:48:52 +0530
Message-ID: <CAA4eK1L-V4eKomAbwFUjD10wEU190YBH28DCEWkNJeO=USHDfA@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <TYCPR01MB8373BA483A6D2C924C600968EDDB9@TYCPR01MB8373.jpnprd01.prod.outlook.com>
	<CAHut+PtXmsRamBH9F7RVkcBzPaetKtcxCAcpoh6RkJOy=AAHWw@mail.gmail.com>
	<TYAPR01MB5866C11DAF8AB04F3CC181D3F5D89@TYAPR01MB5866.jpnprd01.prod.outlook.com>
	<[email protected]>

On Thu, Feb 9, 2023 at 10:45 AM Kyotaro Horiguchi
<[email protected]> wrote:
>
> At Wed, 8 Feb 2023 09:03:03 +0000, "Hayato Kuroda (Fujitsu)" <[email protected]> wrote in
> > Thank you for reviewing! PSA new version.
>
> +               if (statusinterval_ms > 0 && diffms > statusinterval_ms)
>
> The next expected feedback time is measured from the last status
> report.  Thus, it seems to me this may suppress feedbacks from being
> sent for an unexpectedly long time especially when min_apply_delay is
> shorter than wal_r_s_interval.
>

I think the minimum time before we send any feedback during the wait
is wal_r_s_interval. Now, I think if there is no transaction for a
long time before we get a new transaction, there should be keep-alive
messages in between which would allow us to send feedback at regular
intervals (wal_receiver_status_interval). So, I think we should be
able to send feedback in less than 2 * wal_receiver_status_interval
unless wal_sender/receiver timeout is very large and there is a very
low volume of transactions. Now, we can try to send the feedback
before we start waiting or maybe after every
wal_receiver_status_interval / 2 but I think that will lead to more
spurious feedback messages than we get the benefit from them.

-- 
With Regards,
Amit Kapila.






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