International Business Machines Corporation
Method and system for hybrid sort and hash-based query execution

Abstract:

A database system, computer program product, and a method for evaluating aggregates in database systems includes hashing of aggregation keys on a per bucket basis, and depending on a number of hashed tuples per bucket, sorting said tuples. Additionally, depending on the number of hashed tuples per bucket, the bucket is kept without change. Moreover, depending on the number of hashed tuples per bucket, maintaining a secondary hash table for a particular bucket, map tuples to it, aggregate as you map.