Re: composite type and domain

Grzegorz Jaśkiewicz wrote:
> Why is it not possible to create domain on composite type ?
>
> Consider the example, I got (a bytea, b timestamp, c timestamp). Where
> b < c always, and both b and c have some default value, a can stay
> null.
> Now, I don't want to go berserk, and create aditional table for that,
> because type is shared between two tables. But it would be nice, to be
> able to create domain based on that type.
> Any reasons I can't , or is it just something I do wrong?
>
> That's on 8.3/8.4
>

I think Postgres' type system is as good any and better than most...
even if it doesn't do what you are asking. They ALL have their problems.

What I do is handle it in the constructors. So if someone passes b > c
it swaps them. It doesn't help for casts, so I'm careful to always use
the constructors.

I wrote a couple articles about doing this in Postgres and Oracle on my
blog.

http://scottrbailey.wordpress.com/2009/05/19/timespan-postgresql/

Scott