How to Specify the Set of Data that OLAP DML Operations Work Against

Oracle OLAP keeps track of the values of a dimension that are accessible to the user using lists, called "status lists", for each defined dimension.

About Status Lists

Oracle OLAP keeps track of the values of a dimension are accessible to the user using lists, called "status lists" for each defined dimension. There are two kinds of status lists: default status lists and current status lists. The values in the current status lists of the dimensions in an analytic workspace determine the set of data that is available to the OLAP DML at any given moment in time.

Default Status Lists

The the default status list of a dimension is the list of all of the values of the dimension that have read permission, in the order in which the values are stored, when you first attach an analytic workspace. You can change the default status list of a dimension in the following ways:

You can add, delete, move, merge, and rename values in a dimension by using the MAINTAIN command or adding dimension values in other ways (for example, using a SQL FETCH statement).
You can change the read permission of values that are associated with a dimension by using a PERMIT or PERMITRESET statement.

Current Status Lists

The current status list of a dimension is an ordered list of currently accessible values for the dimension. Values that are in the current status list of a dimension are said to be "in status." When you first attach an analytic workspace, the default and current status lists of each dimension are the same.

The current status list of a dimension determines the accessibility of the data in the analytic workspace:

For dimensions, only those dimension values that are in the current status list are visible and accessible to OLAP DML expressions.
For dimensioned objects like variables, only those data values that are indexed by dimension values in the current status list are visible and accessible to OLAP DML expressions. As a loop is performed through a dimensioned object, the order of the dimension values in the current status list is used to determine the order in which the values of the object are accessed.

Note that a dimension and any surrogate for that dimension share the same status. Setting the status of a dimension surrogate sets the status of its dimension and setting the status of a dimension sets the status of any dimension surrogates for it. Throughout this documentation, references to dimensions apply equally to dimension surrogates, except where noted. Additionally, composites are not dimensions, and therefore they do not have any independent status. The values of a composite that are "in status" are determined by the status of the base dimensions of the composite.

Note:

Whether or not a dimension value is in status merely restricts the OLAP DML's view of the value during a given session; it does not permanently affect the values that are stored in the analytic workspace.

Changing the Current Status of a Dimension to Work with a Subset of Data

Since the current status list of a dimension determines the accessibility of the data in the analytic workspace, the way to work with a subset of analytic workspace data is to change the current status lists of one or more dimensions.

You change the change the values and the order of the values in the current status list of a dimension using the LIMIT command. The LIMIT command is a very complex OLAP DML command that lets you specify what values you want in the current status list by specifying the values explicitly or implicitly using relations. At it simplest level, Example 10-20, "Using LIMIT to Partially Populate Variables" illustrates how you can use the LIMIT command to change the current status list of a dimension allows you to work with a subset of data.

Saving and Restoring Current Dimension Status

There are several different ways that you can save the current status of a dimension. The scope of each way is different:

Any session—To save the current status for use in any session, create a named valueset with that status. Use a DEFINE VALUESET command to define the valueset. Use a LIMIT command to assign the values to the valueset.
Current session—To save, access, or update the current status for use in the current session, then use a named context. Use the CONTEXT command to define the context.
Current program—To save the current status for use in the current program, then use the PUSHLEVEL and PUSH commands. You can restore the current status values using the POPLEVEL and POP commands.

Using a Subset of Data Without Changing Status

Sometimes you want to have an individual OLAP DML statement or expression work against a subset of data without actually changing the current status list of a dimension. To support this need, some OLAP DML statements allow you to specify the name of a previously-defined valueset object instead of the name of a dimension. Additionally, on-the-fly, you can specify the data subset that you want without changing the current status list of dimensions using one of the following:

The CHGDIMS function which, during the evaluation of expression, changes the dimensionality of an expression or changes the dimension status.
The LIMIT function which, during the evaluation of expression, returns the dimension or dimension surrogate values that result from a specified LIMIT command or a specified dimension status stack.
Use a qualified data reference (QDR) which is a way of limiting one or more dimensions of an expression to a single value when you want to specify a single value of a data object without changing the current status.