1 Copyright © 2006, Oracle. All rights reserved. Defining OLAP Concepts

1-2 Copyright © 2006, Oracle. All rights reserved. Objectives After completing this lesson, you should be able to describe the following: Benefits of using OLAP for end users and for IT Main features of a dimensional model Fundamental concepts of Oracle Database 10g OLAP

1-3 Copyright © 2006, Oracle. All rights reserved. What Is OLAP? OLAP stands for online analytical processing. Online: You have access to live data (rather than static data). Analytical processing: You can analyze your data for reporting. You can create reports that are: –Multidimensional –Calculation rich –Supported by time-based analysis –Ideal for applications with unpredictable, ad hoc query requirements

1-4 Copyright © 2006, Oracle. All rights reserved. Typical Business Questions How do sales for our five most profitable products across the U.S. for this quarter compare with sales a year ago? What are the differences in the product-sales mix between the regions, relative to the global sales mix? What are our forecast units, unit price per service, unit cost per product, sales, cost trends, and profit for the next 12 months? In what ways does the mix vary by salesperson, and what is the relative performance of our salespeople? What are the products making up 40% of our profit for each region over time?

1-5 Copyright © 2006, Oracle. All rights reserved. Examining an OLAP Question An OLAP question is a multidimensional query, as in the following: –For each region of the world, what was the percentage change in revenue for our top 20% products, over a rolling three-month period this year compared to the same period last year? This is a simple business question, but the actual query can be quite complex.

1-6 Copyright © 2006, Oracle. All rights reserved.

1-7 Copyright © 2006, Oracle. All rights reserved. Dimensional Model The multidimensional logical model has the following elements: Measures Dimensions –Hierarchies –Levels –Attributes

1-8 Copyright © 2006, Oracle. All rights reserved. Measures Represent factual data Are organized by one or more dimensions Populate the cells of a logical cube Can be numeric data, text, dates, Booleans, and so on

1-9 Copyright © 2006, Oracle. All rights reserved. Measure Types Measures are of two types: Stored measures store the result in data cells. Calculated measures evaluate calculated data from a formula.

1-10 Copyright © 2006, Oracle. All rights reserved. Example of Measures in a Report

1-11 Copyright © 2006, Oracle. All rights reserved. Dimensions Dimensions: Form the “edges” of the measure Provide pointers to the actual cells inside the multidimensional measures Q1 Q2 Q3 Q4 Time Product Africa Europe Asia Americas SALES measure Regions Laptop Camcorder Camera LCD monitor

1-12 Copyright © 2006, Oracle. All rights reserved. Example of Dimensions in a Report

1-13 Copyright © 2006, Oracle. All rights reserved. Sharing Dimensions Time Product Customer UNITS Time Product Customer SALES Time Product PRICE

1-14 Copyright © 2006, Oracle. All rights reserved. Hierarchy A hierarchy is a parent-child relationship between the members of a dimension. Hierarchies enable logical groupings of dimension members for the purposes of: –Navigation of data –Aggregation of measures –Allocation of data in a budgeting or planning application –Certain calculations, such as shares and indexes Dimensions can have more than one hierarchy.

1-15 Copyright © 2006, Oracle. All rights reserved.

1-16 Copyright © 2006, Oracle. All rights reserved. Hierarchy: Example Hierarchies enable you to navigate from the lowest level to the highest level, or from the highest to the lowest. You can aggregate data from the lowest level to the highest level. Software Hardware PCs Laptops Monitors XMY Z L1L2L3 Y1Y2Y3 Total Product …

1-17 Copyright © 2006, Oracle. All rights reserved. Levels Level All Products Category Subcategory Product Software Hardware Laptops Monitors XMY Z L1L2L3 Y1Y2Y3 Total Product … PCs

1-18 Copyright © 2006, Oracle. All rights reserved. Types of Hierarchy Director VPAdmin Analyst Senior Director VP President Days Months Quarters Years Level-based hierarchy Value-based hierarchy Director Admin

1-19 Copyright © 2006, Oracle. All rights reserved. Attributes Attributes provide descriptive information about the dimension members. Attributes are also useful when you are selecting dimension members for analysis: –Select the products whose color (attribute) is “Blue.” –Select the customers who have two children. –Select the promotions that are of type “Multipack.” –Select all time periods whose description contains “January.”

1-20 Copyright © 2006, Oracle. All rights reserved. Attributes and Levels: Examples TotalCategorySubcategoryProductManagerColor All Products Clothing Women’s Men’s Kids’ Red shirt Green pants Red pants Blue shirt Mary John Mary Red Green Red Blue BeddingSheets Pillows Yellow sheets Red sheets White pillows Karl Bruce Yellow Red White LevelsAttributes

1-21 Copyright © 2006, Oracle. All rights reserved. Dimensional Model Summarized The multidimensional logical model has the following elements: Measures Dimensions: –Hierarchies –Levels –Attributes Time Product Customer Item Brand Manufacturer MonthQuarterYear Sales Product Share Sales Year to Date Profit Average Selling Price

1-22 Copyright © 2006, Oracle. All rights reserved. OLAP: A Historical Perspective Deploy a specialized database that physically stores data in multidimensional form. –For example, Oracle Express, Hyperion Essbase, Microsoft Analysis Services Implement the logical dimensional model by using a “star” or “snowflake” schema in a relational database. –For example, Oracle database, IBM DB2, Microsoft SQL Server SQL Tools SQL OLAP API OLAP Tools

1-23 Copyright © 2006, Oracle. All rights reserved. Benefits: Fast storage and retrieval of data Power and ease of analytical calculations Logical dimensional model favored by users Drawbacks: Extra cost Increased learning curve Limited scalability Deploy a Stand-alone Multidimensional Database OLAP API OLAP Tools

1-24 Copyright © 2006, Oracle. All rights reserved. Implement a Dimensional Schema in an RDBMS Benefits: No extra cost incurred with a proprietary system Familiar relational skills and tools used Easier to store large volumes of data Drawbacks: Performance declines as ad hoc requirements increase Difficult to implement some required calculations Increased workload for IT and end users SQL Tools SQL

1-25 Copyright © 2006, Oracle. All rights reserved. A Compromising Choice SQL OLAP API ?

1-26 Copyright © 2006, Oracle. All rights reserved. Managing Multidimensional Needs with Oracle OLAP 10g Tools Multidimensional data types Relational data types SQL OLAP API Data and business rules

1-27 Copyright © 2006, Oracle. All rights reserved.

1-28 Copyright © 2006, Oracle. All rights reserved. Query Performance Multidimensional data types Relational data types Slower query Faster query Ad Hoc Nature of Application and Query Patterns Less ad hoc Predictable queries Simple calculations More ad hoc Unpredictable query patterns Sophisticated calculations

1-29 Copyright © 2006, Oracle. All rights reserved. Time to Prepare Data for Query More time Less time Ad Hoc Nature of Application and Query Patterns Less ad hoc Predictable queries Simple calculations More ad hoc Unpredictable query patterns Sophisticated calculations Preparation time Relational data types Multidimensional data types

1-30 Copyright © 2006, Oracle. All rights reserved. Summary In this lesson, you should have learned how to describe: The benefits of using OLAP for IT and end users The main elements and terminology of the dimensional data model The fundamental concepts of Oracle Database 10g OLAP

1-31 Copyright © 2006, Oracle. All rights reserved. Practice 1: Overview This practice covers designing a logical multidimensional data model from a simple requirements definition.

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1-36 Copyright © 2006, Oracle. All rights reserved.