Re: WIP: extensible enums

On 23 August 2010 19:25, Joseph Adams <joeyadams3(dot)14159(at)gmail(dot)com> wrote:
> On Mon, Aug 23, 2010 at 1:54 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> "Andrew Dunstan" <andrew(at)dunslane(dot)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?
>

ALTER TYPE colors ADD 'orange';

--
Thom Brown
Registered Linux user: #516935