Parallel query processing, as described in this chapter, means that the same query is run on multiple processors and that each processor accesses in parallel a different subset of the database. Another form of parallel query processing, not discussed in this chapter, would partition the query so that each part of the query runs on a different processor, but that part accesses whatever part of the database it needs. Most queries involve a qualification clause that selects the records of interest in the query. In general, this qualification clause is of the following form:
(condition OR condition OR...) AND (condition OR condition OR...) AND... Given this general form, how might a query be broken apart so that each parallel processor handles a subset of the query and then combines the subsets together after each part is processed?