Re: Strange DOMAIN behavior

On 09.07.2015 17:23, David G. Johnston wrote:
> On Thu, Jul 9, 2015 at 10:10 AM, Alex Ignatov
> <a(dot)ignatov(at)postgrespro(dot)ru <mailto: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.
>
Sorry for top-post.
It is sad but constructor function for composite type doesn't work in
declare block. For example:

CREATE OR REPLACE FUNCTION new_lexema()
RETURNS lexema AS $body$
DECLARE
lex lexema;
BEGIN
lex=ROW ('tt',0);
RETURN lex;
END;
$body$
LANGUAGE PLPGSQL
SECURITY DEFINER;

DROP FUNCTION lexema_test( );
CREATE OR REPLACE FUNCTION lexema_test()
RETURNS VOID AS $body$
DECLARE
lex lexema :=new_lexema();
BEGIN
END;
$body$
LANGUAGE PLPGSQL
SECURITY DEFINER;

Then I got:
ERROR: default value for row or record variable is not supported
LINE 17: lex lexema :=new_lexema();

--
Alex Ignatov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

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