Suggestion for Enum Support Functions

toronto programmer wrote:

Dear Postgres developers,

I have been working with Oracle for few years now in my work, and I
tried some free databases for a project that I'm developing for my own
use, I have tried H2,FireBird and postgres, and found the last to be
the most stable and feature-rich, so thanks for all the good work.

I have read the 8.3 documentation, and with reference to Enum Support
Functions found on
http://developer.postgresql.org/pgdocs/postgres/functions-enum.html, i
think it is useful to add 2 functions, enum_after(anyenum) and
enum_before(anyenum), so having :

CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple');
enum_after('orange'::rainbow) will return 'yellow'
enum_after('purple'::rainbow) will return an error
enum_before('purple'::rainbow) will return 'blue'

a good to have
function would be enum_size(anyenum) which would return 6 in the previous example
that will be helpful in dealing with enums

You could easily create these for yourself, of course. For example:

create or replace function enum_size(anyenum)
returns int as
$$ select array_upper(enum_range($1),1) $$
language sql;

Successor and predecessor functions would be a bit more work, but not
hard. I don't think they should error out at the range extremes, though.
Perhaps returning NULL would be better.

We could look at adding these as builtins for 8.4, but it's too late now
to add them for 8.3. Besides, I think we need to see how enums are used
in the field before deciding if any extensions are needed.

cheers

andrerw