The destroy() support function
The database server calls the destroy() support function for an opaque type when a value is ready to be deleted from an opaque-type column (DELETE or DROP TABLE).
The destroy() support function accepts
the disk internal representation of the opaque data type and does
not return a value, as the following signature shows:
void destroy(disk_internal_rep);- disk_internal_rep
- The appropriate format for the disk internal representation of
the opaque data type. The passing mechanism of this return value depends
on the kind of opaque type. For more information, see Determine the passing mechanism for an opaque type. Tip: Unlike most opaque-type support functions, the destroy() function for an opaque type must have the explicit name destroy when you register it with the CREATE FUNCTION statement. No implicit casting occurs when the database server resolves this function. However, it is recommended that you include the name of the opaque type in the C-language version of its destroy() function.