Re: Add column if not exists (CINE)

On Wed, Apr 28, 2010 at 11:20 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> I don't believe you are fairly stating the consensus from previous
>> discussion and I believe that you are actually in the minority on this
>> one.  I agree that we probably don't need to support this for object
>> types for which CREATE OR REPLACE is available or can be made
>> available, but that isn't feasible for all object types - tables and
>> columns being the obvious examples.
>
> What's obvious about it?  In particular, I should think that ADD OR
> REPLACE COLUMN would usefully be defined as "ADD if no such column,
> else ALTER COLUMN as necessary to match this spec".  Dropping the
> ALTER part of that has no benefit except to lazy implementors; it
> certainly is not more useful to users if they can't be sure of the
> column properties after issuing the command.

Actually, that's a good idea. But how will you handle tables?

...Robert