V$SYS_OPTIMIZER_ENV

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

ID

NUMBER

Unique identifier of the parameter in the optimizer environment

NAME

VARCHAR2(40)

Name of the parameter

SQL_FEATURE

VARCHAR2(64)

Associated feature control ID

ISDEFAULT

VARCHAR2(3)

Indicates whether the parameter is set to the default value (YES) or not (NO)

VALUE

VARCHAR2(25)

Value of the parameter

DEFAULT_VALUE

VARCHAR2(25)

Default value of the parameter

CON_ID

NUMBER

The ID of the container to which the data pertains. Possible values include:

  • 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data

See Also: