My first Publication Agile-Data-Warehouse-Design-eBook | Page 141

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Chapter 4
Modeling the Next Detailed Event
Create a BEAM✲
table for the next
important event and
ask for its when
detail
When you discover an event on the matrix, such as PRODUCT SHIPMENTS (with
an importance of 500), which needs to be modeled in detail, you begin by creating
a new BEAM ✲ table and copying the event main clause to it. But before you copy
any further details, ask for a new when detail to help tell interesting event stories.
For PRODUCT SHIPMENTS you ask:
When does a warehouse worker ship product?
and the stakeholders reply:
On a shipment date.
Reuse conformed
dimensions and
examples wherever
possible
Add this to the table, as in Figure 4-18, and ask for event stories just as you did
with the initial CUSTOMER ORDERS event. The only difference this time is that
you will be using candidate conformed dimensions that already have examples.
You want to re-use these examples where possible, to illustrate the conformance.
Figure 4-18
New PRODUCT
SHIPMENTS
event table
Reusing Conformed Dimensions and Examples
Conformed
examples relate
new event stories to
existing stories
Don’t use cryptic
business keys to
speed up event
story telling
When you use conformed dimensions to describe new events, you should reuse
their existing examples where applicable to help relate new event stories to existing
ones. Once you get into the habit of using conformed examples to show that the
same customers, products, employees, etc. are involved, you will soon want to
minimize the drudgery of duplicating the same examples again and again.
You might be tempted to speed up the process by using shorter business keys
rather than rewriting dimension subjects out in longhand. This may even appear to
be good data modeling practice because event tables will then contain foreign key
references to the dimension business keys that will surely make them easier to