Re: Identify missing publications from publisher while create/alter subscription.

Just wondering if we should also be detecting the incorrect conninfo
set with ALTER SUBSCRIPTION command as well. See below:

-- try creating a subscription with incorrect conninfo. the command fails.
postgres=# create subscription sub1 connection 'host=localhost
port=5490 dbname=postgres' publication pub1;
ERROR:  could not connect to the publisher: connection to server at
"localhost" (::1), port 5490 failed: Connection refused
    Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (127.0.0.1), port 5490 failed:
Connection refused
    Is the server running on that host and accepting TCP/IP connections?
postgres=#
postgres=#

-- this time the conninfo is correct and the command succeeded.
postgres=# create subscription sub1 connection 'host=localhost
port=5432 dbname=postgres' publication pub1;
NOTICE:  created replication slot "sub1" on publisher
CREATE SUBSCRIPTION
postgres=#
postgres=#

-- reset the connninfo in the subscription to some wrong value. the
command succeeds.
postgres=# alter subscription sub1 connection 'host=localhost
port=5490 dbname=postgres';
ALTER SUBSCRIPTION
postgres=#

postgres=# drop subscription sub1;
ERROR:  could not connect to publisher when attempting to drop
replication slot "sub1": connection to server at "localhost" (::1),
port 5490 failed: Connection refused
    Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (127.0.0.1), port 5490 failed:
Connection refused
    Is the server running on that host and accepting TCP/IP connections?
HINT:  Use ALTER SUBSCRIPTION ... SET (slot_name = NONE) to
disassociate the subscription from the slot.

==

When creating a subscription we do connect to the publisher node hence
the incorrect connection info gets detected. But that's not the case
with alter subscription.

--
With Regards,
Ashutosh Sharma.

On Sat, Nov 13, 2021 at 6:27 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Sat, Nov 13, 2021 at 12:50 PM vignesh C <vignesh21@gmail.com> wrote:
> >
> > Thanks for the comments, the attached v13 patch has the fixes for the same.
>
> Thanks for the updated v13 patch. I have no further comments, it looks
> good to me.
>
> Regards,
> Bharath Rupireddy.
>
>