After creating dimensions and cubes, you can identify their data sources in Oracle Database. A mapping identifies this flow of data from the relational source objects to the dimensional target objects. After you have mapped a dimension or a cube, you can load data into it.
Note: If you want to omit one or more levels of detail data from a cube, or perform a calculation on the data for a measure, then refer to Using Expressions in Cube Mappings.
Typically, you only map the base level to a data source, and generate all summary data in the analytic workspace by defining aggregation rules. However, you can map summary data under these circumstances:
The dimension with summary data uses keys from the data source.
The data for all mapped levels is stored in one column.
The following instructions explain how to use the graphical mapping view.
To map a dimension, take these steps:
Define the dimension and its levels, hierarchies, and attributes.
In the navigation tree, expand the dimension folder and click Mappings.
The Mapping Window is displayed in the right pane. You will see a schema navigation tree and a table with rows for the levels and their attributes.
Enlarge the Mapping Window by dragging the divider to the left.
Identify the type of schema: Star, Snowflake, or Other.
Click Help for information about these schema types.
In the schema tree, locate the tables with the dimension members and attributes for all levels. Drag-and-drop them onto the mapping canvas.
You can peruse the contents of a table or view either in the schema tree, or after you drag-and-drop the icon representing the table or view onto the mapping canvas. Right-click the row in the schema tree, or anywhere in the icon, and choose View Data from the pop-up menu.
Draw lines from the source columns to the target objects. To draw a line, click on the output connector of the source column and drag it to the input connector of the target object.
Important: The dimension keys must be unique within a level. If they are not unique, then you must first create a view with unique level keys. You can create a unique key column by concatenating the level keys. For example, if the City column has several values for Springfield, then you can create a view that concatenates the State and City values for the City level, such as MA_Springfield, NJ_Springfield, and VA_Springfield.
To uncross the lines, click the Auto Arrange Mappings tool.
When you have mapped all objects for the dimension, drag the divider to the right to reduce the size of the Mapping Window.
You can now use the navigation tree.
To map a cube, take these steps:
In the navigation tree, expand the cube folder and click Mappings.
The Mapping Window will be displayed in the right pane. You will see a schema tree and a table with rows for the measures, dimensions, and levels.
Enlarge the Mapping Window by dragging the divider to the left.
In the schema tree, locate the tables with the measures. Drag-and-drop them onto the mapping canvas.
Draw lines from the source columns to the target objects. To draw a line, click on the output connector of the source column and drag it to the input connector of the target object.
Important: You must map both the measures and the related dimension keys. If the related dimension keys have been omitted from the cube dimension, then refer to Using Expressions in Cube Mappings.
To uncross the lines, click the Auto Arrange Mappings tool.
When you have mapped all measures in the cube, drag the divider to the right to reduce the size of the Mapping Window.
You can now use the navigation tree.
Locating Source Objects
Using Expressions in Cube Mappings
Copyright © 2003, 2007, Oracle. All rights reserved.