Conclusions

  We summarise the main conclusions that can be drawn form the results that have been described in the previous section:

1.

In all experiments clearly dominates ; can be ignored. This has two consequences:

• It proves that the performance model is largely independent of the underlying parallel programming paradigm, such as message-passing or multithreading, as this fact is mainly relevant for the repartitioning stage.
• When designing partitioning strategies, we can concentrate on optimising .

2.

The CPU time dominates the costs for the three subjoins. Memory costs can become important in the case of a hardware platform in which a large number of processors shares the access to the common main memory (see experiment 1).

3.

The subjoins that involve replicated tuples, i.e. subjoins (a) and (c), become increasingly important

• for large numbers, m, of fragments (see experiment 2),
• for large average interval lengths, (see experiment 4).