Basic Aggregation Methods

• Sort Based : Sort the relation on the attributes on which aggregation needs to be done. Aggregate the tuples which have similar values for the attributes on which aggregation is to be done. Note that, after sorting these tuples come together in the order.
• Hash Based : Hash the tuples on the attributes on which aggregation needs to be done. Since tuples with same values on these attributes will be in the same hash bucket, aggregate each bucket independently.