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Pentaho Documentation

Creating Link Dimensions

Overview

Create a dimension to be reused later by using the Link Dimension in the Annotate Stream step.

Dimensions organize facts and measures so that users can answer business questions quickly. The most common dimension used is a time dimension, but dimensions are also used to classify people (such as customers), geographical places, and product lines.

The Link Dimension annotation allows you to reuse a previously created Shared Dimension. For example, if you want to create a generic dimension for reuse, such as a standard time dimension, you can create a Shared Dimension and then link directly to that dimension's key. This will import all hierarchies from the Shared Dimension into your data model, resulting in a star schema that joins the fact table to the shared dimension table.

Creating a Link Dimension

These steps guide you through creating a link dimension using the Annotate Stream step.

  1. Double click to open up the Annotate Stream dialog.
  2. Click on the Select Fields... button to choose a field to use to create the attribute.
  3. Double click on that field in the list of Annotations.
  4. Select Link Dimension from the Actions menu. The Name - Value columns auto populate with a list of annotation components for the measure.
    1. Enter a name for the dimension.
    2. Choose a Shared Dimension to link to from the dropdown menu.
  5. Click OK to finish the attribute or click Cancel to exit.

Creating a Dimension Key

Before your Link Dimension can be used by others, you must create a dimension key for the shared dimension to link to.

  1. Click on Select Fields to choose a field to use as the dimension key.
  2. Enter a Dimension Name for the key.
  3. Designate the Shared Dimension.
  4. Click OK to finish the attribute or click Cancel to exit.

You can use a single field more than once, so you will be able to use the same field for both the key and to create annotations.

This is an example of the Annotate - Link Dimension dialog box, along with a table that has more details about each field.

LinkDimension.png

Options Description
Name - Value Displays the name of the annotation component. Click in the Value column next to the item that you want to work with.
Dimension Name Type a name for your dimension.
Shared Dimension Shows a list of previously created Shared Dimensions to link to.
Help Provides a link to the Help documentation.
Previous Scrolls back through the list of created annotations on the model.
Next Scrolls forward through a list of created annotations on the model.
OK Click OK to save.
Cancel Click Cancel to close the window.