Oracle 参数 PARALLEL_ADAPTIVE_MULTI_USER 官方解释，作用，如何配置最优化建议
本站中文解释
PARALLEL_ADAPTIVE_MULTI_USER参数的全称为Oracle自适应多用户并发调整参数。该参数用于控制Oracle对于多用户操作时是否自动调整其操作的并发级别，用以减少资源的浪费。
该参数的默认值为FALSE，表示不执行自适应调整；设为TRUE，则Oracle会根据当前的用户数（但不超过最大并发用户数）、服务器状态、用户当前正在执行的操作来自动调节并发程度，为用户提供最佳的操作效率。
一般来说，使用Oracle自适应多用户并发调整参数有利于提高用户体验，但是，如果确实要使用该参数，就必须在正确设置好COMPOSITE_LIMIT和CPU_COUNT参数，因为Oracle自适应调整仅是为控制并发级别，并不是实现资源的优化，不设置此参数，反而会导致系统资源的浪费和浪费。
官方英文解释
PARALLEL_ADAPTIVE_MULTI_USER, when set to true, enables an adaptive algorithm designed to improve performance in multiuser environments that use parallel execution.
| Property | Description |
|---|---|
|
Parameter type |
Boolean |
|
Default value |
|
|
Modifiable |
|
|
Modifiable in a PDB |
No |
|
Range of values |
|
|
Basic |
No |
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.
Tables and hints use the default degree of parallelism.
Note:
The PARALLEL_ADAPTIVE_MULTI_USER initialization parameter is deprecated in Oracle Database 12c Release 2 (12.2.0.1) and may be removed in a future release. Oracle recommends that you use the parallel statement queuing feature instead.
See Also:
-
Oracle Database SQL
Language Reference for more information about optimizer hints -
Oracle Database VLDB and
Partitioning Guide for more information about parallel statement queuing
