SCHEDULING MULTIPLE QUERIES IN SYMMETRICAL MULTIPROCESSORS

Traditionally, queries submitted to a database management system are o ptimized one at a time. However, queries posed to a database usually a ccess some common relations, or share some common intermediate results . Exploiting such sharings can effectively improve the performance of the system. In this paper, we describe our approach to scheduling a gr oup of queries for processing in symmetric multiprocessors. The novel feature of our approach is that we exploit sharings of(base) relations and/or common intermediate results for pipelined plans. We propose an optimization framework that exploits such sharings. Two scheduling al gorithms are derived from the framework. The first algorithm, SerialSh are, generates a serial plan, while the second algorithm, MultiShare, generates a parallel plan. An analytical model is developed to study t he performance of the algorithms. Compared to the traditional method o f executing one query after another without sharing, our results show that our proposed algorithms can provide significant performance impro vement. (C) Elsevier Science Inc. 1996