Oracle 视图 V$SYS_OPTIMIZER_ENV 官方解释，作用，如何使用详细说明
本站中文解释
Oracle 视图（V$SYS_OPTIMIZER_ENV）显示当前优化器环境中各个变量的值。它是一个动态视图，它显示可以通过影响查询优化过程而发生更改的优化器参数。
使用方法：
1.查询所有变量：
“`sql
SELECT * FROM V$SYS_OPTIMIZER_ENV;
“`
2.查询特定的变量：
“`sql
SELECT * FROM V$SYS_OPTIMIZER_ENV
WHERE name = ”;
“`
其中，指的是要查询的变量的名称。
官方英文解释
V$SYS_OPTIMIZER_ENV displays the contents of the optimizer environment for the instance. The optimizer environment stores the value of the main parameters used by the Oracle optimizer when building the execution plan of a SQL statement. Hence, modifying the value of one or more of these parameters (for example, by issuing an ALTER SYSTEM statement) could lead to plan changes.
The parameters displayed by this view are either regular initialization parameters (such as OPTIMIZER_FEATURES_ENABLE) or pseudo parameters (such as ACTIVE_INSTANCE_COUNT).
| Column | Datatype | Description |
|---|---|---|
|
|
|
Unique identifier of the parameter in the optimizer environment |
|
|
|
Name of the parameter |
|
|
|
Associated feature control ID |
|
|
|
Indicates whether the parameter is set to the default value ( |
|
|
|
Value of the parameter |
|
|
|
Default value of the parameter |
|
|
|
The ID of the container to which the data pertains. Possible values include:
|
See Also:
-
“OPTIMIZER_FEATURES_ENABLE”
-
“ACTIVE_INSTANCE_COUNT”
