Re: DOMAINs and CASTs

On Sun, May 15, 2011 at 2:13 AM, Darren Duncan <darren@darrenduncan.net> wrote:
>
>  ('1800-01-01 00:00:00'::timestamp)::int
>
> Now, since all values of a DOMAIN are also values of the base type the
> DOMAIN is defined as being a subset of, then the sub-expression within the
> parenthesis denotes a value that is both a timestamp and a datetime at the
> same time.
>
> So, if a generic "CAST(timestamp as int)" is already defined, and you define
> a "CAST(datetime as int)", then what should the above code (correct for
> misspelling) do, or should it fail?
>

Obviously it should run the cast from timestamp to int, why it will
run a cast from a domain?
the other way should be allowed, though... a cast from datetime to int
should first look for cast function using the domain and if it don't
find it then with base type

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Jaime Casanova         www.2ndQuadrant.com
Professional PostgreSQL: Soporte y capacitación de PostgreSQL