The Step 1 of 3
dialog is a great example of how the wizard makes design straightforward and
rapid - assuming planning (based upon a solid understanding of the business
requirements of the information consumers) has taken place before we
embark upon cube design. We simply select from a list the data source
fields that we wish to present, and how we wish to summarize each of
those fields, in an efficient and easy-to-use screen.
In
this step, it is important that we decide which of our source data fields it
makes sense to use as data fields. Data fields contain values
(that is, they are measures) that we want to summarize, such as
store costs for which information consumers have a need for totals. The
wizard requires that we select at least one field to be a data field.
When the dialog
initially appears, the wizard has several boxes checked already. These are selected
by the well-meaning (but not necessarily correct) wizard, based upon its
conclusion that these fields appear to contain measure-like data. It "proposes"
them, as a result, for selection in this step. It is critical to verify
whether the wizard's proposals are correct, and to make any changes to fit our
business requirements. The fields that we leave unchecked in this step will
comprise the set of available dimension fields in Step 2, from which we
will select and organize those we need to design our dimension hierarchy
structures
18. Fill out the Step 1 0f 3
dialog, ensuring that only the settings in Table 1 below exist (clearing
any unwanted checkboxes).
|
Source Field
|
|
Summarize By
|
|
Data Field Name
|
|
|
|
|
|
|
|
store_sales
|
|
Sum
|
|
Store
Sales
|
|
|
|
|
|
|
|
store_cost
|
|
Sum
|
|
Store
Costs
|
|
|
|
|
|
|
|
unit_sales
|
|
Sum
|
|
Store
Unit Sales
|
Table 1: Initial
Measures List with Suggested New Names
In the above settings, we made
minor modifications to the field names, as we might to fit terminology
that exists in current reports, and so forth.
The OLAP
Cube Wizard - Step 1 of 3 dialog now partially appears, with all relevant
selections displayed, as shown in Illustration 12.
Illustration 12: Step 1
of 3 Dialog (Partial View) with Our Selections
The OLAP
Cube Wizard - Step 2 of 3 dialog appears.
In
this step, we organize the descriptive data into dimensions, each of
which can be used as a field in any report we generate from our cube. The
organization of the fields in levels of detail that we design at this stage
should allow information consumers to select the level of detail
to view, starting with high-level summaries, drilling to details and zooming
back to summaries as appropriate to meet their reporting needs.
The
wizard requires that we designate at least one dimension for a
cube. We can designate fields that provide isolated facts, and do not belong in
any particular hierarchy, such as the Store Type in our example, as dimensions
with a single level. Rather obviously, our cube will be more useful
for reports if we design some of the fields, as levels, to "roll up"
to higher levels and dimensions.
To
create a level within a dimension, drag each field from the Source
Fields list onto an existing dimension or level in the Dimensions
box, as shown in the following steps. To rename a selection, simply
right-click and select Rename from the shortcut menu that appears. (The "click
label and wait" routine also enables the direct typing of changes.)
20. Move the selections shown below in
Table 2 from the Source fields ("Table Name" in Table
2) list on the left to the appropriate position in the Dimensions
list on the right. (To correctly place the dimensions / levels
under the dimensions, use the "template" guide that
automatically adjusts itself to remain at the bottom of the existing Dimension
list, for each new dimension created.)
21. Rename each "Table Name"
selection, with the suggested "New Name" below it, as shown in
Table 2. (See Illustration 13, below Table 2, to clarify
any confusion as to placement).
|
|
Dimension
|
Level1
|
Level2
|
Level3
|
|
Table
Name
|
product_category
|
product_category
|
product_subcategory
|
product_name
|
|
New
Name
|
Product
|
Category
|
Subcategory
|
Product
Name
|
|
Table
Name
|
sales_country
|
sales_country
|
sales_state_province
|
sales_city
|
|
New
Name
|
Sales
|
Sales
Country
|
Sales State
|
Sales City
|
|
Table
Name
|
store_country
|
store_country
|
store_state
|
store_city
|
|
New
Name
|
Store
|
Store
Country
|
Store State
|
Store City
|
|
Table
Name
|
the_year
|
the_year
|
quarter
|
the_month
|
|
New
Name
|
Time
|
Year
|
Quarter
|
Month
|
Table 2: Initial
Dimensions List with Suggested New Names
The OLAP
Cube Wizard - Step 2 of 3 dialog now resembles that partially illustrated
in Illustration 13.
Illustration 13: Partial
View of Step 2 of 3 Dialog with Our Selections
The OLAP
Cube Wizard - Step 3 of 3 dialog appears.
23. Select the radio button with the
caption Save a cube file containing all data for the cube by clicking
it, if necessary.
24. Select a convenient location in
which to save the cube file. (I left mine at default.)
25. Click Save, as required.
The OLAP
Cube Wizard - Step 3 of 3 dialog now appears similar to Illustration 14
below.
Illustration 14: Step 3
of 3 Dialog with Cube Type Selection and File Name / Location
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