Distinct Data Types

A distinct data type is a user-defined data type that is based on an existing built-in type, opaque type, named row type, or distinct type. To create a distinct type, you must use the CREATE DISTINCT TYPE statement. (For more information, seeCREATE DISTINCT TYPE.)

DISTINCT column values cannot be retrieved by a distributed query (nor modified by INSERT, DELETE, or UPDATE operations on a remote database) unless the base type is a built-in data type, and all of the tables that the DML operation accesses are in databases of the local Dynamic Server instance.

Values of a DISTINCT data type can be returned from a remote database by a UDR only if all of the following conditions are true:

• the DISTINCT type is defined on a built-in data type
• the DISTINCT type can be explicitly cast to a built-in data type
• the DISTINCT type, its explicit cast to a built-in type, and the UDR are defined in all participating databases, and
• all of the databases are databases of the local Dynamic Server instance.