Home > SSAS > SSAS #24 – Implement Attribute Relationship in SSAS 2008

SSAS #24 – Implement Attribute Relationship in SSAS 2008

Do you still remember the blue squiggly from my previous blog post, SSAS #23 – Implement dimensional hierarchy in SSAS 2008?

On the Hierarchies tab in the Dimension Designer, the blue squiggly says:

“Attribute relationships do not exist between one or more levels in this hierarchy. This may result in decreased query performance.”

You’ve already know that this is a Best Practice Warning and it is telling us to create attribute relationships.

Fortunately, in SSAS 2008, attribute relationships are no longer a “hidden” feature, as in SSAS 2005 where there is no graphic to show the relationships. Now we have a dedicated tab with graphics. How cool can it get?

After the drag-and-drop of the two attributes, TreatmentType and Treatment, to the Hierarchies tab, the initial graphics on the Attribute relationships shows:

image  

This is not exactly correct.

The correct graphics should be:

image

The trick here is to create the attribute relationships in reverse, that is, lower-order objects (many) then higher-order objects (one), instead of in the order of one-to-many.

There are two ways to get the relationships into the correct order.

One way –drag the lower-order object and drop in onto the higher-order object

Give it a try. Drag Treatment and drop it onto TreatmentType.

Another way – use the Attribute Relationships pane at the lower right corner.

Right click on the relationship. Select Edit Attribute Relationship…

image

Make sure these:

  • The One side of the relationship = Source Attribute
  • The Many side of the relationship = Related Attribute
  • Relationship type = Rigid (in my example, the relationship will not change over time)
  •  

image

The blue squiggly on the Hierarchies tab disappeared

Here is the proof.

image

Closing Remark

In SSAS #22, 23 and 24 posts, I made the following assumptions:

  • you will use the star schema in your data mart design, and
  • there are natural one-to-many relationships among dimensional attributes, therefore,
  • the dimensional hierarchical structures are stored in one single dimensional table, and
  • the dimensional table is a non-parent-child table
    There are many discussions about Snowflake schema verses Star schema. If you use a Star schema, the Dimension Wizard will not be able to detect the natural hierarchies that exist.
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: