V$SES_OPTIMIZER_ENV displays the contents of the optimizer environment used by each session. When a new session is first created, it automatically inherits its optimizer environment from the optimizer environment defined at the instance level by V$SYS_OPTIMIZER_ENV. The value of certain parameters can be dynamically modified by issuing an ALTER SESSION statement.

Column Datatype Description
SID NUMBER Session identifier. This column can be used to join with V$SESSION on the SID column.
ID NUMBER Unique identifier of the parameter in the optimizer environment
NAME VARCHAR2(40) Name of the parameter
ISDEFAULT VARCHAR2(3) Indicates whether the parameter is set to the default value (YES) or not (NO)
VALUE VARCHAR2(25) Value of the parameter for the session