Conformed Dimensions

Report
Bus Matrix…
the foundation of your Data Warehouse
Bill Anton
Prime Data Intelligence
About Me
• I Love Data!
• …also, Microsoft DW/BI (MCTS/MCITP, MCSA/MCSE)
• Independent Consultant @ Prime Data Intelligence, LLC
• Atlanta BI SQL Server Users Group
• Twitter:
• Blog:
• Email:
@SQLbyoBI
http://byoBI.com
[email protected]
What we will cover today 
• Dimensional Modeling 101
• What, Why, How
• Common Challenges
• Bus Matrix
• What is it?
• How does it help?
• Examples
What is Dimensional Modeling?
Facts
• additive amounts
• E.g. Sales amount, inventory quantity
• SUM, AVERAGE, MAX, MIN, COUNT
Dimensions
• descriptive attributes
• E.g. Date, Product, Location, Customer
• GROUP BY <attribute>, <attribute>, etc
What is Dimensional Modeling?
DIMENSION
DIMENSION
DIMENSION
FACT
DIMENSION
DIMENSION
“Star Schema”
What is Dimensional Modeling?
• Denormalization
• “Repeating Values”
• Opposite of “normalized” (e.g. 3rd Normal Form)
• Optimized for reads (not writes)
Dimensional Modeling 101
Question: What are the most common types of Data
Warehouse methodologies/architectures?
• Kimball
• Inmon
• Data Vault
Dimensional Modeling 101
Question: For which of these DW methodologies should you
include a dimensional model?
Kimball, Inmon, Data Vault
All of them 
Kimball Dimensional DW
Source
Stage
DW
Cubes
Inmon 3NF EDW + Data Mart(s)
Source
Stage
3NF DW
Data Marts
Cubes
Data Vault + Data Mart(s)
Source
Stage
Data Vault
DW
Data Marts
Cubes
Why Dimensional Modeling
• Intuitive to Business Users
• Simpler than OLTP/3NF
• Rise of Self-Service (E.g. Power Pivot, Power View)
• Iterative Development
• “Agile”
• Performance
• Optimized for analytical queries
e.g. sales amount by product in 2013 for top 10 all-time customers
• And many more…
See Teo Lachev’s “WHY SEMANTIC LAYER” newsletter:
http://www.prologika.com/Newsroom/Newsletter2013Fall.aspx
Intuitive to Business Users
Dimensions
Dimensions
Facts
How many bikes did we sell last year?
Do we sell more bikes to single or married
females?
What was our most/least profitable product
this year?
What was the Average Monthly Gross Margin
Return on Inventory Investment (GMROII) by
Product Category for the trailing 6 months?
It’s Complicated
Star-Schema
Date
DIMENSION
DIMENSION
DIMENSION
Customer
Product
Sales
FACT
DIMENSION
DIMENSION
Store
Sales Person
1 “Star” per Fact table
Date
Date
Product
Customer
Sales
Sales Person
Sales Process
Inventory
Store
Product
Store
Inventory Process
Facts are related through dimensions…
Date
Date
Customer
Product
Sales
Sales Person
Sales Process
Inventory
Store
Store
Product
Inventory Process
Facts “Conformed
are related
through dimensions…
Dimensions”
A conformed dimension is a set of data attributes that have
Customer
Date
been physically referenced by multiple
fact tables using the
same key value to refer to the same structure, attributes,
domain values, definitions and concepts.
Dimensions are
conformed when they
are either exactly Inventory
the
Sales
Product
same (including keys) or one is a perfect subset of the
other.
Dimension tables are NOT conformed if the attributes are
Sales Person
Store
labeled differently or contain different values.
Dimensions: Conformed vs Unconformed
Revisiting Average Monthly Gross Margin
Return on Inventory Investment (GMROII)
Customer
Date
Sales
Sales Person
Average Monthly
GMROII
Product
Inventory
Store
Profit for total
time period
Sum of each month
ending inventory cost
What was the Average Monthly Gross Margin
Return on Inventory Investment (GMROII) by
Product Category for the trailing 6 months?
Where things start to get complex…
• 1 Star per Fact table
• Multiple Fact tables per business process
• Multiple business processes in an enterprise
Dimensional Model becomes a “Galaxy of Stars”
Finance
Production
Sales
Distribution
HR
ER Diagram: Adventure Works Sample DW
For bigger Data Warehouses…
This ^^
Turns into this ^^
Variety of Problems to Overcome with
Dimensional Modeling
• Communication & Strategy
• What’s the short term plan of attack?
• What’s the long term plan of attack?
• Documentation
• What’s in our Data Warehouse?
• Business Users can’t read ER diagrams
• Business Users are typically only familiar with a 1 or 2 business processes
• E.g. Sales User vs Inventory User; Warehouse Supervisor vs CEO
• Conforming Dimensions is hard…REALLY hard
• So are changes (E.g. Impact Analysis)
What’s the Solution?
• Train business users to read ER Diagrams?
• Simplify Data Model?
• Ignore certain business processes?
• Don’t use Conformed Dimensions?
• Force business users to manually map data between processes?
What about a Bus Matrix?
What is a Bus Matrix?
2-dimensional visualization
showing the intersection of
facts and dimensions
Variety of Use-Cases for a Bus Matrix
• Documentation, Communication, Training
• Facilitate User Adoption of BI tools
• Communicate Expectations w/ Business
• New users unfamiliar with new business process
• Team Development
• Agile
• Prioritization of Tasks
• Divide & Conquer
• Road-Mapping
• Prioritization of Business Processes in a Business Intelligence
“Program”
Documentation For Business
Documentation for IT
Master Bus Matrix
Team Development
Sprint 1
Internet Sales
Sprint 2
Reseller Sales
Road-Mapping
When To Create a Bus Matrix
• During Requirements Gathering
• Before You Start Development!
• Updated Over Time
• Changes to Business Processes
• New Source Systems (E.g. mergers/acquisitions)
How To Create a Bus Matrix
Manual via Excel
Automated via SSRS
Manual
• Only option when starting out ;-)
• Updates can be made quickly made as
requirements come in
• Adds development overhead, but the
ROI is well worth it
Automated
• Reporting pack with drill-through to
data dictionary information
• Can be based on Cube or Relational
Database (*FK required)
• Incorporate query statistics to
visualize common usage patterns
• Use MDS to allow SME’s to manage
business definitions
Based on example from Alex Whittles
http://www.purplefrogsystems.com/blog/2010/09/olap-cube-documentation-in-ssrs-part-1/
QUESTIONS
References
Twitter: @SQLbyoBI
Blog:
http://byoBI.com
Email: [email protected]
http://byobi.com/blog/bus-matrix/

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