Re: ALTER composite type does not work, but ALTER TABLE which ROWTYPE is used as a type - works fine

On Thu, Dec 4, 2008 at 9:53 AM, Dmitry Koterov <dmitry@koterov.ru> wrote:
> Hello.
>
> I can successfully ALTER a NON-EMPTY table (ct) which ROWTYPE is used as a
> column type for another table (dt):
>
> CREATE TABLE ct (id INTEGER);
> CREATE TABLE dt (id INTEGER, c ct);
>
> INSERT INTO dt VALUES(1, '(666)');
> SELECT * FROM dt;
> -- (1, '(666)')
>
> ALTER TABLE ct ADD COLUMN n INTEGER;
> SELECT * FROM dt;
> -- (1, '(666,)')
>
> You see, '(666,)' means that the new field is added successfully.
>
>
> But, if I declare ct as a COMPOSITE type (not a table), it is not permitted
> to ALTER this type (Postgres says that there are dependensies on ct).
> Why?

Because of this there is no reason to ever use 'create type'....always
use 'create table'.  'alter type' can't add/remove columns anyways.

merlin

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