Re: WIP: extensible enums

On Mon, Aug 23, 2010 at 1:54 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Andrew Dunstan" <andrew@dunslane.net> writes:
>> On Mon, August 23, 2010 11:49 am, Alvaro Herrera wrote:
>>> What do you need AFTER for?  Seems to me that BEFORE should be enough.
>>> (You already have the unadorned syntax for adding an item after the last
>>> one, which is the corner case that BEFORE alone doesn't cover).
>
>> You're right. Strictly speaking we don't need it. But it doesn't hurt much
>> to provide it for a degree of symmetry.
>
> I'm with Alvaro: drop the AFTER variant.  It provides more than one way
> to do the same thing, which isn't that exciting, and it's also going to
> make it harder to document the performance issues.  Without that, you
> can just say "ADD BEFORE will make the enum slower, but plain ADD won't"
> (ignoring the issue of OID wraparound, which'll confuse matters in any
> case).

But what if you want to insert an OID at the end?  You can't do it if
all you've got is BEFORE:

CREATE TYPE colors AS ENUM ('red', 'green', 'blue');

If I want it to become ('red', 'green', 'blue', 'orange'), what am I to do?