Need to increase the query performance - response (2) by tdice

 As suggested by doneth, Change the target table(PAMKTB.CUSTOMER_POS) as a MULTISET TABLE. Then in your select statement add group by condition to remove duplicate records getting inserted to the table. This will load your table in maximum of 10-15 mins.
Your query is taking time because of the SET table and customer_name is not unique primary index, causing the inserted rows to be checked multiple times for same customer name.