Extend prebuilt dimensions with additional attributes from another data
source. For example, you can create a category column that isn't available in the prebuilt
dimensions.
You can define a sort order column to control the sorting order of a logical column, especially when the desired sort order doesn't match the natural sort order of the data. This is useful for situations like sorting months in a specific chronological order or sorting descriptive columns based on a code or hierarchy. Refer to Extend Dimension in the Extending section in Recommendations and Tips to Extend the Semantic Model.
- In step 1 of the Extend a Dimension wizard, select a schema and table from the
database.
- Select the columns that you want to expose or use as a key for creating the
join, or sort by.
- Click in the Display Name table field to enter a new
name for the column or to edit an existing one and then click
Enter to accept or click Esc
to cancel.
- In Sort Order Column, select applicable values in
Sort Order Column for the columns that you selected
to expose or use as a key.
Ensure that the sort order column is within the same hierarchical
level as the display column. For columns not requiring a custom sort, leave the
sort order column in the default Select state.
- If any of the selected attributes have been removed or modified in the source
table since the last refresh, then you see such columns highlighted and a
message asking whether you want to update the table. Select
OK in the message to reload the source columns. If
you want to review the changes to the source columns, then click
Cancel in the message, and later click
Refresh to reload the source columns.
If any of the attributes that you haven’t selected have been removed or
modified in the source table, then you see the refreshed list of source columns.
If any of the custom columns fail validation during the refresh, then you see a
message asking you to resolve the cause of failure and revalidate.
- Optional: Click Create Column to add another column to your
dimension table in the target subject area using these instructions:
- In Create Column, enter a display name.
- Under Data Elements, search for a data element
from the physical table of the selected dimension table.
- From the search results, double-click the data element to place it in
the text pane.
- Under Functions, search for a function to
construct a column using expressions. For example, search for functions
like "substring" or "concatenate" to construct new expression-based
columns. From the search results, double-click the applicable result to
add it to the central text pane.
- Click Validate, and then click
Save.
- Click Next.
- In step 2 of the wizard, select the join type, and then select the dimension
keys to join them with the extended dimension keys. If you want to provide
expressions as join conditions, then click Complex Join
and in Create Joins, click Add Joins, select the target
and source logical tables, enter the join condition as an expression, and click
OK.
- Click Finish.