Re: Ability to listen on two unix sockets

On lör, 2012-06-09 at 18:26 -0400, Tom Lane wrote:
> > Yes, I'm just pointing out that we already have that list
> > (unix_socket_directory in postgresql.conf), except it's currently
> > limited to length 1, because no one has needed a longer one until
> now.
> 
> That's not actually quite the same thing as what I suggest above.
> Currently, unix_socket_directory *overrides* the compiled-in choice.
> I'm suggesting that it would be better to invent a list that is *added
> to* the compiled-in choice.  If we think it would be best to still be
> able to override that, then I'd vote for keeping unix_socket_directory
> as is, and then adding a list named something like
> "secondary_socket_directories".   But if we just turn
> unix_socket_directory into a list, I think the lack of separation
> between primary and secondary directories will be confusing.

By that logic, any list-valued parameter should be split into a primary
and secondary setting.  That could actually be moderately useful in some
cases (think search_path, or if we get there, multiple port settings),
but then we should put this into the grammar or processing logic of
postgresql.conf, not invent a bunch of new settings.  (E.g.,
unix_socket_directory += ...).