Message-ID: <681e1874-0a79-4a01-8536-f358f37fd3f0@gmail.com>
Date: Fri, 27 Oct 2023 17:30:20 +0200
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Subject: Re: Synchronizing slots from primary to standby
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To: Amit Kapila <amit.kapila16@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, Peter Smith
 <smithpb2250@gmail.com>, "Hayato Kuroda (Fujitsu)"
 <kuroda.hayato@fujitsu.com>,
 Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
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 Bruce Momjian <bruce@momjian.us>, Ashutosh Sharma <ashu.coek88@gmail.com>,
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 pgsql-hackers <pgsql-hackers@postgresql.org>,
 Ajin Cherian <itsajin@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>
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From: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
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Hi,

On 10/27/23 10:35 AM, Amit Kapila wrote:
> On Wed, Oct 25, 2023 at 3:15 PM Drouvot, Bertrand
> 
> I think even if we provide such an API, we need to have logic to get
> the slots from the primary and create them.

Yeah, my idea was to add an API (in addition to what is already in place).

> Say, even if the user used
> the APIs, there may still be some new slots that the sync worker needs
> to create. 

Right.

> I think it might be better to provide a view for users to
> view the current state of sync. For example, in the above case, we can
> say "waiting for the primary to advance remote LSN" or something like
> that.

We are already displaying the wait event "ReplSlotsyncPrimaryCatchup" in pg_stat_activity
so that might already be enough?

My main idea was to be able to manually create/sync logical_slot2 in the test case described in [1]
without waiting for activity on logical_slot1.

But another (better?) option might be to change our current algorithm during slot creation on the
standby? (to avoid an "active" slot having to wait on a "inactive" one, like described in [1]).

[1]: https://www.postgresql.org/message-id/afe4ab6c-dde3-48ea-acd8-6f6052c7b8fd%40gmail.com

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com