Is it good to creating SET table with UPI or NUPI and why..? - response (3) by AB75150

SET table with UPI is always better because it enforces the uniquencess of the data in turn it ensures that data is distributed across AMPS evenly. A evenly distributed data improves the performance of the retrieval.
As Rajeev rightly mentioned, if you define a NUPI, then the SET operation needs to scan the entire row ensure that there are no row duplicates. Hope this helps.