Re: Strange DOMAIN behavior

On Thu, Jul 9, 2015 at 10:10 AM, Alex Ignatov <a(dot)ignatov(at)postgrespro(dot)ru>
wrote:

> Thank you for your reply.
> In fact i want to use domains in the following case:
>
> DROP DOMAIN lexema_str CASCADE;
> CREATE DOMAIN lexema_str TEXT DEFAULT 'abc' NOT NULL;
> DROP TYPE lexema_test CASCADE;
> CREATE TYPE lexema_test AS (
> lex lexema_str,
> lex2 BIGINT
> );
> DROP TABLE ttt;
> CREATE TABLE ttt (
> a lexema_test,
> b BIGINT
> );
> INSERT INTO ttt (b) VALUES (1);
> SELECT *
> FROM ttt;
> a | b
> ---+---
> | 1
> (1 row)
>
> a.lex is null again not 'abc' as I expected like in plpgsql.
>
> All i want is to have default values in composite types. Feature that
> Oracle have.
> I thought that with domain type it should be possible.
>
>
Please don't top-post.

So even though ​there is no default specified for column a you expect there
to be a non-null value even though the column was omitted from the insert
statement? I doubt that such a change in behavior would be accepted.

​As far as I know the less-redundant way to accomplish your goal is to
create a constructor function for the type (CREATE FUNCTION default_type()
RETURNS type) and call it where you need to interject a default.

CREATE TABLE ttt ( a lexema_test DEFAULT ROW(default_type(),
NULL)::lexema_test​ )

There likely isn't any hard reasons behind the lack of capabilities wrt.
defaults and composites/domains; its just that no one has been bothered
enough to affect change.

David J.