Re: Logical Replication - behavior of ALTER PUBLICATION .. DROP TABLE and ALTER SUBSCRIPTION .. REFRESH PUBLICATION

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Logical Replication - behavior of ALTER PUBLICATION .. DROP TABLE and ALTER SUBSCRIPTION .. REFRESH PUBLICATION
Date: 2021-01-12 03:37:49
Message-ID: CAA4eK1+ZZWj78SRMrC7hkRLsiKisZW1GDV9Szx9DviK7g4hguA@mail.gmail.com
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On Mon, Jan 11, 2021 at 6:51 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> Hi,
>
> While providing thoughts on the design in [1], I found a strange
> behaviour with the $subject. The use case is shown below as a sequence
> of steps that need to be run on publisher and subscriber to arrive at
> the strange behaviour. In step 5, the table is dropped from the
> publication and in step 6, the refresh publication is run on the
> subscriber, from here onwards, the expectation is that no further
> inserts into the publisher table have to be replicated on to the
> subscriber, but the opposite happens i.e. the inserts are still
> replicated to the subscriber. ISTM as a bug. Let me know if I'm
> missing anything.
>

Did you try to investigate what's going on? Can you please check what
is the behavior if, after step-5, you restart the subscriber and
separately try creating a new subscription (maybe on a different
server) for that publication after step-5 and see if that allows the
relation to be replicated? AFAIU, in AlterSubscription_refresh, we
remove such dropped rels and stop their corresponding apply workers
which should stop the further replication of such relations but that
doesn't seem to be happening in your case.

--
With Regards,
Amit Kapila.

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