Re: promotion related handling in pg_sync_replication_slots()

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: shveta malik <shveta(dot)malik(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>
Subject: Re: promotion related handling in pg_sync_replication_slots()
Date: 2024-04-04 11:46:49
Message-ID: CAA4eK1+MVF7xfeB+oprEHfdCL4tdiZv1kQ8=2FhdTq=XL18u2w@mail.gmail.com
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On Thu, Apr 4, 2024 at 5:05 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> Hello hackers,
>
> Currently, promotion related handling is missing in the slot sync SQL
> function pg_sync_replication_slots(). Here is the background on how
> it is done in slot sync worker:
> During promotion, the startup process in order to shut down the
> slot-sync worker, sets the 'stopSignaled' flag, sends the shut-down
> signal, and waits for slot sync worker to exit. Meanwhile if the
> postmaster has not noticed the promotion yet, it may end up restarting
> slot sync worker. In such a case, the worker exits if 'stopSignaled'
> is set.
>
> Since there is a chance that the user (or any of his scripts/tools)
> may execute SQL function pg_sync_replication_slots() in parallel to
> promotion, such handling is needed in this SQL function as well, The
> attached patch attempts to implement the same.
>

Thanks for the report and patch. I'll look into it.

--
With Regards,
Amit Kapila.

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