internal error(00801) on combining two collections in oracle 10g

问题

hos := hos1 multiset union hos2;

The statement throws internal error, where hos, hos1 and hos2 are of same object type

回答1:

This error seems to have been fixed on Oracle 11. For previous versions, you need to add a map member function.

alter type my_object_type add map member function dummy return number invalidate;

来源：https://stackoverflow.com/questions/35934650/internal-error00801-on-combining-two-collections-in-oracle-10g