Re: CountDBSubscriptions check in dropdb

On Mon, Oct 21, 2019 at 11:43 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> While reviewing Pavel's patch for a new option in Drop Database
> command [1], I noticed that the check for CountDBSubscriptions in
> dropdb() is done after we kill the autovac workers and allowed other
> backends to exit via CountOtherDBBackends.  Now, if there are already
> active subscritions due to which we can't drop database, then it is
> better to fail before we do CountOtherDBBackends.  It is also
> indicated in a comment (
> check this after other error conditions) that CountOtherDBBackends has
> to be done after error checks.
>
> So, I feel we should rearrange the code to move the subscriptions
> check before CountOtherDBBackends as is done in the attached patch.
>
> This has been introduced by below commit:
> commit 665d1fad99e7b11678b0d5fa24d2898424243cd6
> Author: Peter Eisentraut <peter_e@gmx.net>
> Date:   Thu Jan 19 12:00:00 2017 -0500
>
>     Logical replication
>

I am planning to commit and backpatch this till PG10 where it was
introduced on Monday morning (IST).  Pavel agreed that this is a good
change in the other thread where we need it [1].  It is not an urgent
thing, so I can wait if we think this is not a good time to commit
this.  Let me know if anyone has objections?


[1] - https://www.postgresql.org/message-id/CAFj8pRD75_wYzigvhk3fLcixGSkevwnYtdwE3gf%2Bb8EqRqbXSA%40mail.gmail.com

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com