A new algorithm for small-large table outer joins in parallel DBMS

Large enterprises have been relying on parallel database management systems (PDBMS) to process their ever-increasing data volume and complex queries. Business intelligence tools used by enterprises frequently generate a large number of outer joins and require high performance from the underlying database systems. A common type of outer joins in business applications is the small-large table outer join studied in this paper where one table is relatively small and the other is large. We present an efficient and easy to implement algorithm called DER (Duplication and Efficient Redistribution) for small and large table outer joins. Our experimental results show that the DER algorithm significantly speeds up query elapsed time and scales linearly.