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Oracle® OLAP DML Reference 10g Release 2 (10.2) Part Number B14346-01 |
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# Running a Model

When you run a model, you should keep these points in mind:

- Before you run a model, the input data must be available in the solution variable.

- Before running a model that contains a block of simultaneous equations, you might want to check or modify the values of some OLAP DML options that control the solution of simultaneous blocks. These options are described briefly in Table A-7, "Model Options".

- When your model contains any dimension-based equations, then you must provide a numeric solution variable that serves both as a source of data and as the assignment target for equation results. The solution variable is usually dimensioned by all of the dimensions on which model equations are based and also by the other dimensions of the solution variable on which you are not basing equations.

- When you run a model, a loop is performed automatically over the values in the current status list of each of the dimensions of the solution variable on which you have not based equations.

- When a model equation bases its calculations on data from previous time periods, then the solution variable must contain data for these previous periods. When it does not, or when the first value of the dimension of type DAY, WEEK, MONTH, QUARTER, or YEAR is in status, then the results of the calculation are `NA`.

## Syntax for Running a Model

To run or solve a model, use the following syntax.

model-name [solution-variable] [NOWARN]

where:

- model-name is the name of the model.

- solution-variable is the name of a numeric variable that serves as both the source and the target of data in a model that contains dimension-based equations. The solution variable is usually dimensioned by all the dimensions on which model equations are based (as specified in explicit or included DIMENSION commands). The solution-variable argument is required when the model contains any dimension-based equations. When all the model equations are based only on variables, a solution variable is not needed and an error occurs when you supply this argument. See "Dimensions of Solution Variables" for more information on dimensions of solution variables.

- NOWARN is an optional argument that specifies that you do not want to be warned when the model contains a block of simultaneous equations.

## Dimensions of Solution Variables

In a model with dimension-based equations, the solution variable is usually dimensioned by the dimensions on which model equations are based. Or, when a solution variable is dimensioned by a composite, the model equations can be based on base dimensions of the composite. The dimensions on which model equations are based are listed in explicit or inherited DIMENSION (in models) commands.

### Special Cases of Solution Variables

The following special cases regarding the dimensions of the solution variable can occur:

- The solution variable can have dimensions that are not listed in DIMENSION commands. Oracle OLAP automatically loops over the values in the status of the extra dimensions. For example, the model might contain a DIMENSION statement that lists the `line` and `month` dimensions, but you might specify a solution variable dimensioned by `line`, `month`, and `division`. Oracle OLAP automatically loops over the `division` dimension when you run the model. The solution variable can also be dimensioned by a composite that has one or more base dimensions that are not listed in DIMENSION commands. See "Solution Variables Dimensioned by a Composite".

- When the solution variable has dimensions that are not listed in DIMENSION commands and when any of these other dimensions are the dimension of a step or simultaneous block, an error occurs.

- Oracle OLAP loops over the values in the status of all the dimensions listed in DIMENSION commands, regardless of whether the solution variable is dimensioned by them. Therefore, Oracle OLAP will be doing extra, unnecessary work when the solution variable is not dimensioned by all the listed dimensions. Oracle OLAP warns you of this situation before it starts solving the model.

- The inclusion of an unneeded dimension of type DAY, WEEK, MONTH, QUARTER, or YEAR in a DIMENSION statement causes incorrect results when you use a loan, depreciation, or aggregation function in a model equation. This happens because any component of a model equation that refers to the values of a model dimension behaves as if that component has all the dimensions of the model.

### Solution Variables Dimensioned by a Composite

When a solution variable contains a composite in its dimension list, Oracle OLAP observes the sparsity of the composite whenever possible. As it solves the model, Oracle OLAP confines its loop over the composite to the values that exist in the composite. It observes the current status of the composite's base dimensions as it loops.

However, for proper solution of the model, Oracle OLAP must treat the following base dimensions of the composite as regular dimensions:

- A base dimension that is listed in a DIMENSION (in models) statement.

- A base dimension that is implicated in a model equation created using SET (for example, an equation that assigns data to a variable dimensioned by the base dimension).

- A base dimension that is also a base dimension of a different composite that is specified in the ACROSS phrase of an equation. (See SET for more information on assignment statements and the use of ACROSS phrase.)

When a base dimension of a solution variable's composite falls in any of the preceding three categories, Oracle OLAP treats that dimension as a regular dimension and loops over all the values that are in the current status.

When the solution variable's composite has other base dimensions that do not fall in the special three categories, Oracle OLAP creates a temporary composite of these extra base dimensions. The values of the temporary composite are the combinations that existed in the original composite. Oracle OLAP loops over the temporary composite as it solves the model.