Building the cube – Chapter 9 & 10

Let’s be over with it

Two SSMS (SQL Server Management Studio)

• Important for any tasks deals with databases• Use this to make sure the

MaxMinMangufactureingDM database is in working order, follow the instructions I posted

• It is a Data Mart SSDT (SQL Server Data Tool)

• Essentially Visual Studio 2010• Creating a Multidimensional BI Semantic Model

(OLAP) and DM projects use the same tool

Key Steps 1 – need to know where to find this tool, you

may have to start a new project

Key steps 1 – may want to find the right directory to

store your projects 8 – you may have to create a new

connection

Key Steps 8 – Impersonation,

pick the first one• You can have

multiple data sources for the same project

Measures and related

Measure Group• The table where the measure comes from• The data in the table is the source for the

measure

Other factors to consider Granularity

• How detailed view do we need Day, month, quarter, year, etc. Professor, department, division, college, university

Calculated measures• New measures generated through calculations

with existing ones• For example, the total goods produced = goods

passed QA + goods failed QA• Step 24 of page 345 is another one.

Measure Aggregates beside SUM Look into AggregateFunction property, you

will see a list of selections because not all aggregates are just sum

For example, inventory level is not additive along the time dimension, but additive along the product dimension

Aggregate FunctionsSelection Description

Sum Specifies the sum of members. This is the default aggregation function.

Count Specifies the count of measure members.

Min Specifies the minimum value of members.

Max Specifies the maximum value of members.

DistinctCount Specifies the count of distinct measure members.

NoneNo aggregations are performed on any dimension – data is only available on the leaf cells. If no value from the fact table has been read in for a member, then the cell value for the member is considered to be Null.

ByAccountSpecifies that the aggregation used will be determined for each CurrentMember of the Account dimension according to its account type. Unmapped account types aggregate as SUM.

AverageOfChildren Specifies average of leaf descendants in time. Average does not count an empty value as 0.

FirstChild Specifies the first child member along Time dimension.

LastChild Specifies the last child member along Time dimension.

FirstNonEmpty Specifies the first non empty child member along Time dimension.

LastNonEmpty Specifies the last non empty child member along Time dimension.

Adding new measure group

True we can add new measure groups, but generally believe is to plan ahead and add all measure groups at the very beginning.

What is a measure group? • It is basically a fact table

Types of dimensions

Fact dimensions • Dimensions come from the fact table

Parent Child dimensions• Two columns in the same table• Self reference • For example, employees and managers both

come from the employee table

Types of dimensions

Role playing dimensions• The same dimension can related to multiple

columns multiple times• For example, a time dimension can related to a

sales measure group several times, order date, shipment date, received date, payment received date

Types of dimensions Reference dimensions

• It related to the measure group through another dimension

• In the case below, Geography dimension is related to InternetSales through Customer, therefor is a reference dimension

DM dimensions, M:N dimension, and Slowly changing dimension

The values of the dimension come from data mining algorithms

Many-to-Many dimension• Not to use

Slowly changing dimension • Type 1• Type 2• Type 3

Slowly Changing Dimension As the name suggest

• An employee got promoted in Dec of 2012, she is not the GM, but was a vendor manager before, how to reflect that?

• There are many ways to deal with this. We introduce three common approaches names Type I, II, and III.

The discussions here are based on Wikipedia

Slowly Changing Dimension – type I

Before

After

Then, the “After” info is all you going to see

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co CA

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co IL

Slowly Changing Dimension – type II Before

After

Then, add additional info

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co CA

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co IL

Supplier_Key Supplier_Code Supplier_Name Supplier_State Version.

123 ABC Acme Supply Co CA 0

124 ABC Acme Supply Co IL 1

Supplier_Key Supplier_Code Supplier_Name Supplier_State Start_Date End_Date

123 ABC Acme Supply Co CA 01-Jan-2000 21-Dec-2004

124 ABC Acme Supply Co IL22-Dec-2004

Slowly Changing Dimension – type III Before

After

Then, add additional info

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co CA

Supplier_Key Supplier_Code Supplier_Name Supplier_State

123 ABC Acme Supply Co IL

upplier_Key

Supplier_Code

Supplier_NameOriginal_Supplier_State

Effective_Date

Current_Supplier_State

123 ABCAcme Supply Co

CA22-Dec-2004

IL

Slowly Changing Dimension – type IV Type IV

Type II

SCD– another example Per http://www.learndatamodeling.com First price

Second price

SCD– another example Type I

Use the second price to replace all the first one, actually the first will not be in the DM

SCD– another example Type II Approach I – use product ID and Year as key

Approach II, convert year to Effective DT

SCD– another example Type III

Add, previous price and year

The difference Between Type III and Type II

When we add more product price change,• Type II can be unlimited in handling the

changes by just adding records• Type III can only handle a limit changes, let it be

the first and last, the last two, or some others

Deploying and Processing Deploying

• Send your definitions to the Analysis Services

Processing • Perform the all prescribed calculations

Tools are• MSDT – to deploy and process (trigger these activities)• SSMS – to check the results• Analysis Services Deployment Wizard – a more

advanced tool that generate script for automated deployment to production -- skip

Other Bells and Whistles Linked Object – especially linked measures

• Allowed to combine other cubes to an existing one

BI wizard• A tool allows you to do a number of capability

easily Define time intelligence

• Period to date calculation, rolling average, period-over-period growth

Define currency conversion

Other Bells and Whistles KPI

• The dashboard to indicate how things are going Actions

• Making cube even fancier by allowing other activities such as following a URL, allowing drill-through, or launching a Reporting Service report

Partitions• Break one cube to several cubes for concurrent

processing to improve performance Partitions and storage options MOLAP, ROLAP

Other Bells and Whistles Aggregation Design

• How much aggregation is performed • Two approaches: usage based or manual• Usage based is determined by checking the

usage log• Manual is where the developers specify

Perspectives – very much like views Translations – at metadata level