Processing temporal aggregates in parallel

Temporal databases maintain past, present and future data. TSQL2 is a query language designed for temporal databases. In TSQL2, the GROUP BY clause has the temporal grouping property. In temporal grouping, the time line of each attribute value is partitioned into several sections, and aggregate functions are computed for each time partition. This paper describes two approaches to parallelising an algorithm for computing temporal aggregates. The two approaches have been implemented on an SGI PowerChallenge SMP parallel system. The experimental results show that the performance of the two approaches depends on data skew ratio and the number of processors used in the computation.