The following factors describe the general performance considerations associated with UPIs.
- UPIs guarantee an even distribution of table rows across the AMPs when the number of unique values exceeds that number of AMPs on the system.
- UPIs guarantee the best retrieval and update performance for single table row access.
- UPI values are never associated more than one base table row.
- UPIs retrievals and updates never require spool.
- Uniqueness is enforced by the system using the UPI (thereby avoiding the need for duplicate row checks for multiset tables).