Export support function

The export function takes as an argument the internal structure for the opaque type and a structure that holds the bulk-copy format of the external representation of the opaque type.

If you do not provide an export support function, the database server uses the output support function to export text data.

For C language support, the following function signature is for an export support function of an opaque data type whose internal structure is ll_longlong_t: 
mi_impexp * ll_longlong_export(ll_long_t *intrnl_bcopy_format);

The ll_longlong_export() function is a cast function from the ll_longlong_t internal structure to the IMPEXP data type. It must be registered as an explicit cast function with the CREATE EXPLICIT CAST statement. For more information about cast functions, see Create casts for opaque data types.