[HACKERS] Create subscription with `create_slot=false` and incorrect slot name

[Dmitry Dolgov]

Hi

Maybe this question was already raised before, but I couldn't find a
discussion. When I'm creating a subscription with `create_slot=false` looks
like it's possible to pass a slot name with invalid characters. In this
particular case both publisher and subscriber were on the same machine:

    =# CREATE SUBSCRIPTION test_sub CONNECTION 'dbname=db host=host
port=port user=user' PUBLICATION test_pub WITH (create_slot=false,
slot_name='test slot');
    NOTICE:  00000: synchronized table states
    LOCATION:  CreateSubscription, subscriptioncmds.c:443
    CREATE SUBSCRIPTION
    Time: 5.887 ms

Of course `test slot` doesn't exist, because I can't create a slot with
incorrect name. And consequently I can't drop this subscription:

    =# DROP SUBSCRIPTION test_sub;
    ERROR:  XX000: could not drop the replication slot "test slot" on
publisher
    DETAIL:  The error was: ERROR:  replication slot name "test slot"
contains invalid character
    HINT:  Replication slot names may only contain lower case letters,
numbers, and the underscore character.
    LOCATION:  DropSubscription, subscriptioncmds.c:947
    Time: 2.615 ms

    =# CREATE SUBSCRIPTION test_sub CONNECTION 'dbname=db host=host
port=port user=user' PUBLICATION test_pub WITH (create_slot=false,
slot_name='test slot');
    ERROR:  42710: subscription "test_sub" already exists
    LOCATION:  CreateSubscription, subscriptioncmds.c:344
    Time: 0.492 ms

Is it an issue or I'm doing something wrong?