Re: [BUGS] BUG #5218: Easy strategic feature requests

On Sun, Nov 29, 2009 at 1:57 PM, Craig Ringer
<craig(at)postnewspapers(dot)com(dot)au> wrote:
> Rather than implementing SHOW (blah) as wrappers for selects from views in
> the backend, though, IMO it'd make a lot more sense to provide minimal stubs
> that raised an exception telling the user the right way to do it.
>
> "SHOW TABLES is a MySQL-specific command that isn't part of the SQL standard
> and isn't used by other databases. Please query the SQL-standard
> INFORMATION_SCHEMA instead, or for interactive work use psql's \d command."

And hopefully a URL to a page that gives more details on
INFORMATION_SCHEMA, including the specific commands for the equivalent
of SHOW TABLES etc? Okay, fair enough, that would still provide most
of the benefit.

> In theory, PostgreSQL could be reworked to support changing databases within
> a connection. In practice ... eek. From my minmimal understanding of the
> codebase, enabling a backend to switch databases would require a huge
> overhaul of authentication, backend startup and management, shared memory
> management, and more.

eek indeed! Right, it's definitely not worth that sort of headache. An
error message explaining the situation would provide much of the
benefit for orders of magnitude less cost.