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本站中文解释
CONTAINERS_PARALLEL_DEGREE参数控制表空间操作的并行度。该参数允许的最大值是分区的数量，复制的表空间数量必须比其小，且必须是此数值的因子。
CONTAINERS_PARALLEL_DEGREE参数的值由两个因素决定：一是系统的可用资源，如内存和CPU。二是操作表空间所涉及的表空间比例，如果表空间比例过小，可能无法进行有效的并行操作，故参数的值需要在可用资源的范围内选择合适的值。
正确设置CONTAINERS_PARALLEL_DEGREE参数：
首先，根据系统的可用资源（如内存或者CPU）确定该参数的最大值。其次，根据各个表空间涉及的操作类型，确定该参数的最小值，使得能够得到更好的并行度。最后，在最小值与最大值之间，根据需要选择合适的 CONTAINERS_PARALLEL_DEGREE 值。
官方英文解释
CONTAINERS_PARALLEL_DEGREE can be used to control the degree of parallelism of a query involving containers().
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
|
|
Modifiable |
|
|
Modifiable in a PDB |
Yes |
|
Range of values |
Cannot be set to a value lower than |
|
Basic |
No |
|
Oracle RAC |
Different values can be set on different instances. |
The value of CONTAINERS_PARALLEL_DEGREE, if set, will override the default DOP for a containers() query.
By default, a containers() query uses a degree of parallelism equal to (1 + number of open PDBs) in the case of CDB root and (1 + number of open application PDBs) in the case of application root.
If the value of CONTAINERS_PARALLEL_DEGREE is lower than 65535, then this value is used as the degree of parallelism of a query involving containers(). Otherwise (when the value is 65535), the default degree of parallelism is (1 + number of open PDBs) or (1 + number of open application PDBs) as described above.
See Also:
-
Oracle Multitenant
Administrator’s Guide for more information about CDB roots -
Oracle Multitenant
Administrator’s Guide for more information about application roots
