PARALLEL_ADAPTIVE_MULTI_USER

Parameter type:	Boolean
Parameter class:	Dynamic. Scope = ALTER SYSTEM.
Default value:	Derived from the value of PARALLEL_AUTOMATIC_TUNING
Range of values:	TRUE | FALSE
PARALLEL_ADAPTIVE_MULTI_USER, when set to TRUE, enables an adaptive algorithm designed to improve performance in multi-user environments that use parallel execution. The algorithm automatically reduces the requested degree of parallelism based on the system load at query startup time. The effective degree of parallelism is based on the default degree of parallelism, or the degree from the table or hints, divided by a reduction factor.
The algorithm assumes that The system has been tuned for optimal performance in a single-user environment, The parameter PARALLEL_AUTOMATIC_TUNING parameter is set to TRUE, and Tables and hint use the default degree of parallelism.
See Also: Oracle8i Designing and Tuning for Performance for more information on tuning parallel execution and on the algorithm described here.