set table with sum vs multiset with no sum - response (2) by M.Saeed Khurram

Hi,
You have not provided information about the indexes, the second confusing thing is whether you are trying to insert the individual rows, or you need to insert aggregates? What I suppose is you want to insert aggregate rows, So if the index on the target table is UPI, then in case of SET tables, dup check will be reduced to UPI only and will be much faster.
In case of multiset the duplicates will not be inserted due to UPI. So please confirm if the Index of the table and also if you need to retain the Duplicate rows or just individual rows?