3 Workspace Manager Valid Time Support

This chapter describes the support for valid time, also known as effective dating, with version-enabled tables.

It contains the following major sections:

• Valid Time Support: Introduction and Example
  Some applications need to store data with an associated time range that indicates the validity of the data. That is, each record is valid only within the time range associated with the record.
• WM_PERIOD Data Type
  The WM_PERIOD data type is used to specify a valid time range for the session or workspace, and for a row in a version-enabled table.
• Valid Time Constants
  The following table lists constants that can be used in the validFrom and validTill timestamps of a WM_PERIOD specification.
• 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.
• Operators for Valid Time Support
  Workspace Manager provides relationship checking operators and set operators that accept two time period parameters and that can be used to apply valid time filters in a query.
• Queries and DML Operations with Valid Time Support
  This section describes some behaviors and considerations for queries and data manipulation language (insert, update, and delete) operations related to valid time support.
• Constraint Management for Valid Time Support
  This section describes considerations related to valid time support that affect referential integrity constraints and unique constraints.
• Locking with Valid Time Support
  If a row in a version-enabled table with valid time support is locked, it is automatically locked for its entire valid time period. There is no way to lock a row for a specified time period.
• Static Data Dictionary Views Affected by Valid Time Support
  This section describes the effect on valid time support on Workspace Manager static data dictionary views.
• Adding Valid Time Support to an Existing Table
  You can add valid time support to an existing version-enabled table.
• Merging and Refreshing Workspaces for Tables with Valid Time Support
  When tables that have valid time support are merged or refreshed, you can determine the resulting rows by considering the distinct cases when there is an intersection between rows for the same primary key value.