On 23 August 2010 19:25, Joseph Adams <joeyadams3.14159@gmail.com> wrote:
> 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?
>
ALTER TYPE colors ADD 'orange';
--
Thom Brown
Registered Linux user: #516935