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Re: [HACKERS] Why forcing Hot_standby_feedback to be enabled whencreating a logical decoding slot on standby - Mailing list pgsql-hackers

From sanyam jain
Subject Re: [HACKERS] Why forcing Hot_standby_feedback to be enabled whencreating a logical decoding slot on standby
Date
Msg-id BM1PR01MB1011CDA3F7607F96EA932706C0C10@BM1PR01MB1011.INDPRD01.PROD.OUTLOOK.COM
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In response to Re: [HACKERS] Why forcing Hot_standby_feedback to be enabled whencreating a logical decoding slot on standby  (Michael Paquier <michael.paquier@gmail.com>)
Responses Re: [HACKERS] Why forcing Hot_standby_feedback to be enabled whencreating a logical decoding slot on standby  (Andres Freund <andres@anarazel.de>)
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Isn't XLogRecord carries full information to be decoded in itself?If so a VACCUM should not be a problem in decoding?

Thanks
Sanyam Jain

From: Michael Paquier <michael.paquier@gmail.com>
Sent: Monday, June 12, 2017 6:52:06 AM
To: sanyam jain
Cc: Pg Hackers
Subject: Re: [HACKERS] Why forcing Hot_standby_feedback to be enabled when creating a logical decoding slot on standby
 
On Mon, Jun 12, 2017 at 3:16 PM, sanyam jain <sanyamjain22@live.in> wrote:
> I have created a logical decoding slot on a standby but i haven't enabled
> Hot_standby_feedback.What are the test cases where this setup will fail?

hot_standby_feedback needs to be enabled at all times in logical
decoding so as the node does not remove rows that are still needed for
the decoding, and a VACUUM passing by with a minimal xmin too high
would cause inconsistent decoded data.
--
Michael

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