Re: Need Force flag for pg_drop_replication_slot()

On 2015-05-29 14:39:02 -0400, Stephen Frost wrote:
> * Andres Freund (andres@anarazel.de) wrote:
> > How is this measurably worse than trying to truncate a log table that
> > has grown too large? That's often harder to fight actually, because
> > there's dozens of other processes that might be using the relation?  In
> > one case you don't have wait ordering, but only one locker, in the other
> > case you have multiple waiters, and to benefit from wait ordering you
> > need multiple sessions.
> 
> Because we don't fall over if we can't extend a relation.
> 
> We do fall over if we can't write WAL.

As nearly everybody uses the same filesystem for pg_xlog and the actual
databases, that distinction isn't worth much. You'll still fail when
writing the WAL, even if the disk space has been used by a relation
instead of WAL.