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Module 1: Introduction to Data Warehousing and OLAP

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Module 1: Introduction

to Data Warehousing

and OLAP

Raw Data vs. Business Information

„Capturing Raw Data

z Gathering data recorded in everyday operations

„Deriving Business Information

z Deriving meaningful information from raw data

„Turning Data into Information

z Implementing a decision support system

OLTP Source Systems

„OLTP System Characteristics

zProcesses real-time transactions of a business

zContains data structures optimized for entries and edits

zProvides limited decision support capabilities

„OLTP Examples

zOrder tracking

zCustomer service

zPoint-of-sales

zService-based sales

zBanking functions

Data Warehouse Characteristics

„Provides Data for Business Analysis Processes

„Integrates Data from Heterogeneous Source Systems

„Combines Validated Source Data

„Organizes Data into Non-Volatile, Subject-Specific Groups

„Stores Data in Structures that Are Optimized for Extraction and Querying

Data Warehouse System Components

Data Warehouse

Data Access

User Data Access Data

Sources

Data Input Staging

Area

Data Marts

‹ Defining OLAP Solutions

„OLAP Databases

„Common OLAP Applications

„Relational Data Marts and OLAP Cubes

„OLAP in SQL Server 2000

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OLAP Databases

„Optimized Schema for Fast User Queries

„Robust Calculation Engine for Numeric Analysis

„Conceptual, Intuitive Data Model

„Multidimensional View of Data

zDrill down and drill up

zPivot views of data

Common OLAP Applications

„Executive Information Systems

z Performance measures

z Exception reporting

„Sales/Marketing Applications

z Booking/billing

z Product analysis

z Customer analysis

„Financial Applications

z Reporting

z Planning

z Analysis

„Operations Applications

z Manufacturing

z Customer service

z Product cost

Relational Data Marts and OLAP Cubes

Relational Data Mart Relational Relational Data Mart

Data Mart OLAP CubeOLAP CubeOLAP Cube

Data Storage

Data Storage Relational

Data Structure Relational

Data Structure N-dimensional Data structure N-dimensional Data structure

Data Content

Data Content Detailed and

Summarized Data Detailed and

Summarized Data Summarized DataSummarized Data

Data Sources

Data Sources Relational and

Non-relational Sources Relational and

Non-relational Sources Relational and Non-relational Sources

Relational and Non-relational Sources

Data Retrieval

Data Retrieval Fast Performance for Data Extract Queries Fast Performance for

Data Extract Queries Faster Performance for Data Extract Queries Faster Performance for

Data Extract Queries

OLAP in SQL Server 2000

„Microsoft Is One of Several OLAP Vendors

„Analysis Services Is Bundled with Microsoft SQL Server 2000

„Analysis Services Include

zOLAP engine

zData mining technology

‹ Understanding Data Warehouse Design

„The Star Schema

„Fact Table Components

„Dimension Table Characteristics

„The Snowflake Schema

The Star Schema

Fact Table Dimension Table

Employee_Dim Employee_Dim Employee_Dim EmployeeKey EmployeeKey EmployeeID ...

EmployeeID ...

Time_Dim Time_Dim Time_Dim TimeKey TimeKey TheDate ...

TheDate ...

Product_Dim Product_Dim Product_Dim ProductKey ProductKey ProductID ...

ProductID ...

Customer_Dim Customer_Dim Customer_Dim CustomerKey CustomerKey CustomerID CustomerID Shipper_Dim

Shipper_Dim Shipper_Dim ShipperKey ShipperKey ShipperID ShipperID

Sales_Fact Sales_Fact TimeKey EmployeeKey ProductKey CustomerKey ShipperKey TimeKey EmployeeKey ProductKey CustomerKey ShipperKey Sales Amount Unit Sales ...

Sales Amount Unit Sales ...

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Fact Table Components

Dimension Tables Dimension

Tables

customer_dim customer_dim customer_dim 201 ALFI Alfreds 201 ALFI Alfreds

product_dim product_dim product_dim 25 123 Chai 25 123 Chai

sales_fact Table

Measures Measures

customer_key

customer_keyproduct_keyproduct_keytime_keytime_keyquantity_salesquantity_salesamount_salesamount_sales Foreign Keys

Foreign Keys

201 25 134 400 10,789

The grainof the sales_fact table is defined by the lowest level of detail stored in each dimension

134 1/1/2000 134 1/1/2000time_dim time_dim time_dim

Dimension Table Characteristics

„Describes Business Entities

„Contains Attributes That Provide Context to Numeric Data

„Presents Data Organized into Hierarchies

The Snowflake Schema

„Defines Hierarchies by Using Multiple Dimension Tables

„Is More Normalized than a Single Table Dimension

„Is Supported within Analysis Services

‹ Understanding OLAP Models

„OLAP Database Components

„OLAP Dimensions vs. Relational Dimensions

„Dimension Fundamentals

„Dimension Family Relationships

„Cube Measures

„Relational Data Sources

OLAP Database Components

„Numeric Measures

„Dimensions

„Cubes

REGION

West CA

East OR

MA NY

REGION

West East

STATE REGION

CA West

OR West

MA East

NY East

OLAP Dimensions vs. Relational Dimensions

OLAP Relational

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Dimension Fundamentals

USANorth West Oregon Washington South West

California USANorth West Oregon Washington South West

California USANorth West Oregon Washington South West

California USANorth West Oregon Washington South West

California USANorth West Oregon Washington South West

California USANorth West Oregon Washington South West

California

Dimension Family Relationships

‹ USA is the parent of North West and South West

‹ North West and South West are children of USA

‹ North West and South West are siblings

‹ North West and California are descendants of USA

‹ North West and USA are ancestors of Washington

‹ Oregon and California are cousins

‹ All are dimension members USANorth West

Oregon Washington South West

California USANorth West Oregon Washington South West

California

Cube Measures

„Are the Numeric Values of Principle Interest

„Correspond to Fact Table Facts

„Intersect All Dimensions at All Levels

„Are Aggregated at All Levels of Detail

„Form a Dimension

Relational Data Sources

„Star and Snowflake Schemas

zAre required to build a cube with Analysis Services

„Fact Table

zContains measures

zContains keys that join to dimension tables

„Dimension Tables

zMust exist in same database as fact table

zContain primary keys that identify each member

‹Applying OLAP Cubes

„Defining a Cube

„Querying a Cube

„Defining a Cube Slice

„Working with Dimensions and Hierarchies

„Visualizing Cube Dimensions

„Connecting to an OLAP Cube

Defining a Cube

Q1 Q2 Q3 Q4

Time Dimension Products Dimension Detroit

Denver Chicago

Market Dimension

Apples CherriesGrapes Atlanta

Melons

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Q1 Q2 Q3 Q4 Time Dimension

ProductsDimension Dallas

Denver Chicago

MarketsDimension

Apples CherriesGrapes

Atlanta Sales

Fact

Melons

Querying a Cube

Apples Q1 Q2 Q3 Q4

Time Dimension

ProductsDimension Detroit

Denver Chicago Atlanta

Markets Dimension

MelonsCherriesGrapes

Defining a Cube Slice

Working with Dimensions and Hierarchies

„Dimensions Allow You to

zSlice

zDice

„Hierarchies Allow You to

zDrill Down

zDrill Up

Visualizing Cube Dimensions

Connecting to an OLAP Cube

0 1000 2000 3000 4000 5000 6000

Bagels Muffins Sliced Bread Cheese Deli Meats Frozen Chicken

Bread Dairy Meat

Sheri Now mer - 2001 - Quarter 4 Sheri Now mer - 2001 - Quarter 3 Sheri Now mer - 2001 - Quarter 2 Sheri Now mer - 2001 - Quarter 1 Sheri Now mer - 2000 - Quarter 4 Sheri Now mer - 2000 - Quarter 3 Sheri Now mer - 2000 - Quarter 2 Sheri Now mer - 2000 - Quarter 1 State USA

Sales Units

Category Subcategory

Level 02 Year Quarter

Review

„Introducing Data Warehousing

„Defining OLAP Solutions

„Understanding Data Warehouse Design

„Understanding OLAP Models

„Applying OLAP Cubes

References

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