1.256 PARALLEL_DEGREE_POLICY
PARALLEL_DEGREE_POLICY
specifies whether automatic degree of parallelism, statement queuing, and in-memory parallel execution will be enabled.
Property | Description |
---|---|
Parameter type |
String |
Syntax |
|
Default value |
|
Modifiable |
|
Modifiable in a PDB |
Yes |
Basic |
No |
Values
Note:
Automatic degree of parallelism will be enabled regardless of the value of PARALLEL_DEGREE_POLICY
if a PARALLEL
hint is used at the SQL statement level.
-
MANUAL
Disables automatic degree of parallelism, statement queuing, and in-memory parallel execution. This reverts the behavior of parallel execution to what it was prior to Oracle Database 11g Release 2 (11.2). This is the default.
-
LIMITED
Enables automatic degree of parallelism for some statements but statement queuing and in-memory Parallel Execution are disabled. Automatic degree of parallelism is only applied to those statements that access tables or indexes decorated explicitly with the
DEFAULT
degree of parallelism using thePARALLEL
clause. Statements that do not access any tables or indexes decorated with theDEFAULT
degree of parallelism will retain theMANUAL
behavior. -
AUTO
Enables automatic degree of parallelism, statement queuing, and in-memory parallel execution.
-
ADAPTIVE
This value enables automatic degree of parallelism, statement queuing and in-memory parallel execution, similar to the
AUTO
value. In addition, performance feedback is enabled. Performance feedback helps to improve the degree of parallelism automatically chosen for repeated SQL statements. After the initial execution of a statement, the degree of parallelism chosen by the optimizer is compared to the degree of parallelism computed based on the actual execution performance. If they vary significantly, then the statement is marked for re-parse and the initial execution performance statistics (for example, CPU-time) are provided as feedback for subsequent executions. The optimizer uses the initial execution performance statistics to better determine a degree of parallelism for subsequent executions.
See Also:
-
Oracle Database SQL Language Reference for information about
PARALLEL
hints -
Oracle Database VLDB and Partitioning Guide for information about automatic degree of parallelism