PARALLEL_MIN_PERCENT

Parameter type	Integer
Default value	0
Parameter class	Dynamic: ALTER SESSION
Range of values	0 to 100
Oracle9i Real Application Clusters	Multiple instances can have different values.

PARALLEL_MIN_PERCENT operates in conjunction with PARALLEL_MAX_SERVERS and PARALLEL_MIN_SERVERS. It lets you specify the minimum percentage of parallel execution processes (of the value of PARALLEL_MAX_SERVERS) required for parallel execution. Setting this parameter ensures that parallel operations will not execute sequentially unless adequate resources are available. The default value of 0 means that no minimum percentage of processes has been set.

Consider the following settings:

PARALLEL_MIN_PERCENT = 50
PARALLEL_MIN_SERVERS = 5
PARALLEL_MAX_SERVERS = 10

If 8 of the 10 parallel execution processes are busy, only 2 processes are available. If you then request a query with a degree of parallelism of 8, the minimum 50% will not be met.

You can use this parameter in conjunction with PARALLEL_ADAPTIVE_MULTI_USER. In a multi-user environment, an individual user or application can set PARALLEL_MIN_PERCENT to a minimum value until sufficient resources are available on the system and an acceptable degree of parallelism is returned.

See Also: Oracle9i Database Performance Guide and Reference for more information on tuning parallel execution "PARALLEL_MAX_SERVERS", "PARALLEL_MIN_SERVERS", and "PARALLEL_ADAPTIVE_MULTI_USER"