Re: [PATCH] Alter or rename enum value

On Mon, Sep 5, 2016 at 11:40 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> The opportunity cost here is potential user confusion. The only
> closely parallel rename operation we have is ALTER TABLE RENAME COLUMN,
> and that doesn't have a column-level IF EXISTS option; it has a
> table-level IF EXISTS option. So I think it would be weird and confusing
> for ALTER TYPE RENAME VALUE to be different from that. And again, it's
> hard to get excited about having these options for RENAME VALUE when no
> one has felt a need for them yet in RENAME COLUMN. I'm especially dubious
> about IF NOT EXISTS against the destination name, considering that there
> isn't *any* variant of RENAME that has an equivalent of that. If it's
> really useful, why hasn't that happened?

Because Tom Lane keeps voting against every patch to expand IF [ NOT ]
EXISTS into a new area? :-)

We do have ALTER TABLE [ IF EXISTS ] .. ADD COLUMN [ IF NOT EXISTS ],
so if somebody wanted the [ IF NOT EXISTS ] clause to also apply to
the RENAME COLUMN case, they'd have a good argument for adding it.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company