Oracle 参数 PARALLEL_MIN_PERCENT 官方解释，作用，如何配置最优化建议
本站中文解释
:
PARALLEL_MIN_PERCENT 是 Oracle 数据库中一个用于管理并行操作的参数。该参数控制能够在并行操作中运行的最小的并行程序的比例。
正确设置该参数的步骤如下：
1.检查系统中当前运行的并行操作程序的数量和宽度，以获取权衡值。
2.根据需求和系统负荷，调整该参数以实现最佳性能。一般来说，将该参数设置为大于25％，以实现最佳性能。
注意：其他一些参数也会影响并行操作的性能，例如：parallel_max_servers，parallel_degree_limit，parallel_execution_message_size，parallel_adaptive_multi_user，etc。应该确保所有这些参数都正确设置。
官方英文解释
PARALLEL_MIN_PERCENT lets you specify the minimum percentage of the requested number of parallel execution processes required for parallel execution.
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
|
|
Modifiable |
|
|
Modifiable in a PDB |
No |
|
Range of values |
0 to 100 |
|
Basic |
No |
|
Oracle RAC |
Multiple instances can have different values. |
This parameter controls the behavior for parallel operations when parallel statement queuing is not enabled (when PARALLEL_DEGREE_POLICY is set to manual or limited). It ensures that an operation always gets a minimum percentage of parallel execution servers or errors out. Setting this parameter ensures that parallel operations will not execute 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 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:
-
Oracle Database SQL Tuning
Guide for more information about parallel execution -
“PARALLEL_DEGREE_POLICY”, “PARALLEL_MAX_SERVERS”, “PARALLEL_MIN_SERVERS”, and “PARALLEL_ADAPTIVE_MULTI_USER”
