3.4 API Features for Valid Time Support

The following table lists DBMS_WM subprograms that are devoted to valid time support or that have parameters related to valid time support.

Table 3-2 API Features for Valid Time Support

Subprogram	Valid Time Support
EnableVersioning	If the validTime parameter value is TRUE, the table is version-enabled with valid time support. A column named WM_VALID of type WM_PERIOD is added to the table. For any existing rows, the WM_VALID column is set with a validFrom timestamp of SYSTIMESTAMP and a validTill timestamp of DBMS_WM.UNTIL_CHANGED.
DisableVersioning	The keepWMValid parameter determines whether to keep (the default) or delete the WM_VALID column and its data when the table is version-disabled.
GetValidFrom	Returns the validFrom timestamp from the session valid time period.
GetValidTill	Returns the validTill timestamp from the session valid time period.
SetValidTime	Sets the session valid time period to the specified range. You can execute the procedure with no parameters (to have the valid time range set as from the current time and until changed), with only the validFrom parameter, or with both the validFrom and validTill parameters.
SetValidTimeFilterOFF	Removes the valid time filter for the current session.
SetValidTimeFilterON	Sets a valid time filter for the current session (that is, a time to be applied to version-enabled tables.
SetWMValidUpdateModeOFF	Disables sequenced and nonsequenced update operations and sequenced delete operations on tables that have valid time support.
SetWMValidUpdateModeON	Enables sequenced and nonsequenced update operations and sequenced delete operations on tables that have valid time support.