Jim Nasby-5 wrote > I'm trying to create what amounts to a new type. This would be rather easy > if I could perform a CHECK on a composite type, which I could do if I > could create a domain on top of a composite. Is there any reason in > particular that hasn't been done? > > As an alternative, I tried accomplishing this with a straight domain. That > would work, except for this: > > WARNING: cast will be ignored because the source data type is a domain > > Why do we ignore casts from domains to other data types? I'm guessing > because it's simply not what domains were meant for?
A domain is a base type with a constraint. When you cast you already know the existing value is valid and the system simply uses the cast available for the base type instead. i.e., You cannot have a domain with a different cast rule than the base type over which it is defined. Likely the lack of capability is simply a matter of complexity in the face of somewhat uncommon usage and limited resources. David J. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Questions-on-domain-on-composite-casts-ignoring-domains-tp5823745p5823763.html Sent from the PostgreSQL - hackers mailing list archive at Nabble.com. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
