When computing the cost of a parallel access method, the optimizer does not consider factors such as the number of engines available, the ratio of engines to CPUs, and whether or not a table’s partitions reside on dedicated physical devices and controllers. Each of these factors can significantly affect the performance of a query. It is up to the System Administrator to ensure that these resources are configured in the best possible way for the Adaptive Server system as a whole.
See “Configuration parameters for controlling parallelism” for information on configuring Adaptive Server.
See “Commands for partitioning tables” on page 106 in the book Performance and Tuning: Basics for information on partitioning your data to best facilitate parallel queries.
