In the same way,
the more serial operations that make up an application, the longer the execution time
will be because the sum of the execution time of all serial operations can offset any
performance gains realized from the use of multiple processors. In other words, you
cannot speed up a serial operation or a sequence of serial operations by adding more
processors.
Clusters | 295
Each subsequent release of Oracle has added more parallelized features to speed up
the execution of queries as well as the tuning and maintenance of the database. For
an extensive list of Oracle operations that can be parallelized, see the section ???What
Can Be Parallelized???? in Chapter 7.
Oracle??™s parallel operations take advantage of available CPU resources. If you??™re
working with a system on which the CPU resources are already being completely
consumed, this parallelism will not help improve performance; in fact, it could even
hurt performance by adding the increased demands for CPU power required to manage
the parallel processes. Oracle??™s adaptive degree of parallelism automatically can
reduce the degree of parallelism for an operation to prevent this situation.
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