After having discussed the initial stage of the optimisation process
in chapter 7, we now want to move on to stage 3 in which
the performance of a partition is determined. The reason for skipping
stage 2 at this point is that we require a good and thorough
understanding of the cost implications for designing partitioning
strategies that are to be employed in stage 2. In order to create
efficient partitions we need to know what the expensive parts of
partitioned temporal join processing are and how these are influenced by
the choice of a partition.
The purpose of this chapter is to create a performance model for partitioned temporal join processing. This model will not only enable us to design efficient partitioning strategies but it is also an integral part of the optimisation process: it is the optimiser's principle tool for deciding on the quality of a particular partition.