Oracle Parallel Processing

Automatic Tuning of Parallel Execution in Oracle8i

With the release of Oracle8i, Oracle has provided some significant additional support for tuning parallel execution environments. Specifically, Oracle now has the ability to make some tuning decisions automatically. If you’ve already manually tuned your application, and it’s performing satisfactorily, automatic tuning may not be beneficial. However, new applications that run on Oracle8i and use Oracle8i ’s parallel execution features can benefit from automatic tuning.

To enable automatic tuning of parallel execution, set the initialization parameter PARALLEL_AUTOMATIC_TUNING to TRUE. At this point, you need to be aware of three effects of automatic tuning:

• The effect of automatic tuning on the default value of the initialization parameters listed in Table 5.5

• The effect of automatic tuning on the adaptive multiuser algorithm

• The effect of the PARALLEL_THREADS_PER_CPU initialization parameter setting

When you set PARALLEL_AUTOMATIC_TUNING = TRUE (thereby enabling automatic tuning of parallel execution), that has an effect on the default values of several initialization parameters. Table 5.5 shows the changes in default values that occur when automatic tuning is used. Remember that you can always override these defaults by explicitly setting the parameters in your initialization file.

Table 5-5. The Effect of Automatic Tuning on Initialization Parameter Defaults

Parameter	Default Value When PARALLEL_AUTOMATIC_TUNING = FALSE	Default ...