带有缓存的Oracle流水线功能

Question

How can use oracle pipelined function on query to fetch data only first time.

example:

create or replace function best_employees return my_type pipelined;

select * from employees a 
join table(best_employees) b 
on a.employee_id = b.employee_id;

this query is calling best_employees function more than one time. It must call only first time. How can i do this. Thanks.

Answer 1

While you could store the results in a package collection of type my_type and write the function to return that if it contained values instead of re-executing the query, the simpler and more reliable approach would be to use the result_cache hint in its query.

select /*+ result_cache */ kitten_id, cuteness from kittens where colour = 'BLACK';

(There is also a result_cache option for functions but it cannot be used for pipelined functions.)