Re: cannot drop replication slot if server is running in single-user mode

On 2018-03-29 17:42:57 -0400, Bruce Momjian wrote:
> On Tue, Mar 6, 2018 at 06:59:33PM +0530, tushar wrote:
> > Hi,
> >
> > I found that if server is running in single-user mode , there we can create
> > replication slot but cannot drop it .
> >
> > backend> SELECT * FROM pg_create_physical_replication_slot('p');
> > 2018-03-06 13:20:03.441 GMT [14869] LOG:  statement: SELECT * FROM
> > pg_create_physical_replication_slot('p');
> >
> >      1: slot_name    (typeid = 19, len = 64, typmod = -1, byval = f)
> >      2: lsn    (typeid = 3220, len = 8, typmod = -1, byval = t)
> >     ----
> >      1: slot_name = "p"    (typeid = 19, len = 64, typmod = -1, byval = f)
> >     ----
> > backend> select pg_drop_replication_slot('p');
> > 2018-03-06 13:20:24.390 GMT [14869] LOG:  statement: select
> > pg_drop_replication_slot('p');
> >
> >      1: pg_drop_replication_slot    (typeid = 2278, len = 4, typmod = -1,
> > byval = t)
> >     ----
> > 2018-03-06 13:20:24.391 GMT [14869] ERROR:  epoll_ctl() failed: Bad file
> > descriptor
> > 2018-03-06 13:20:24.391 GMT [14869] STATEMENT:  select
> > pg_drop_replication_slot('p');
>
> I can confirm this bug exists in single-user mode.

I'm not sure we need to do anything about this, personally. This seems
like a fairly rare thing to do in a mode that's definitely not intended
to be general purpose.

Greetings,

Andres Freund