Tài liệu Module 12: Working with Virtual Cubes docx

Contents Overview 1 Understanding Virtual Cubes 2 Obtaining Logical Results 4 Building a Virtual Cube 5 Lab A: Creating Virtual Cubes 10 Creating Calculated Members 14 Lab B: Adding Calculated Members to a Virtual Cube 16 Review 19 Module 12: Working with Virtual Cubes BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Information in this document is subject to change without notice. The names of companies, products, people, characters, and/or data mentioned herein are fictitious and are in no way intended to represent any real individual, company, product, or event, unless otherwise noted. Complying with all applicable copyright laws is the responsibility of the user. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of Microsoft Corporation. If, however, your only means of access is electronic, permission to print one copy is hereby granted. 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Microsoft is listed first, followed by all other Microsoft trademarks in alphabetical order. > are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and/or other countries. <This is where mention of specific, contractually obligated to, third party trademarks, which are added by the Copy Editor> The names of companies, products, people, characters, and/or data mentioned herein are fictitious and are in no way intended to represent any real individual, company, product, or event, unless otherwise noted. Other product and company names mentioned herein may be the trademarks of their respective owners. Module 12: Working with Virtual Cubes iii BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Instructor Notes A virtual cube is an online analytical processing (OLAP) cube that combines or extracts data from one or more source cubes. These cubes are called virtual because they consume no disk storage, other than metadata. In this module, students learn when to use virtual cubes and the mechanics of how to build them in Microsoft ® SQL Server ™ 2000 Analysis Services. After completing this module, students will be able to: ! Understand when to use virtual cubes and know their benefits. ! Know the rules for constructing meaningful virtual cubes. ! Build virtual cubes by using the Virtual Cube Wizard. ! Define calculated members in virtual cubes by using the Calculated Member Builder. Materials and Preparation This section lists the required materials and preparation tasks that you need to teach this module. Required Materials To teach this module, you need Microsoft PowerPoint ® file 2074A_12.ppt. Preparation Tasks To prepare for this module, you should: ! Read all of the student materials for this module. ! Read the instructor notes and margin notes. ! Complete the labs. ! Review the Trainer Preparation presentation for this module on the Trainer Materials compact disc. ! Review any relevant white papers that are located on the Trainer Materials compact disc. Presentation: 25 Minutes Labs: 20 Minutes iv Module 12: Working with Virtual Cubes BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Other Activities Difficult Questions Below are difficult questions that students may ask you during the delivery of this module and answers to the questions. There materials delve into subjects that are within the scope of the module but are not specifically addressed in the content of the student notes. 1. How does the enabling or disabling of levels in the source cube affect the enabling or disabling of levels in the virtual cube? Enabling or disabling levels in the source cube does not affect the enabling or disabling of levels in the virtual cube. Levels in the source cube are completely separate from levels in the virtual cube, so that, when users are using a virtual cube, they can access members for querying or for creating calculations down to the lowest level in the dimension, regardless of level enabling or disabling in the source cube. 2. Can you add a virtual dimension to a virtual cube without also adding the dimension on which the virtual dimension depends? No. When you add a virtual dimension to a virtual cube, the regular dimension is added to the virtual cube automatically. 3. Can you base virtual cubes on linked cubes? Yes. 4. When you process a source cube, are all virtual cubes that use the source cube data automatically processed? No. 5. Can a virtual cube combine source cubes that use multidimensional OLAP (MOLAP), relational OLAP (ROLAP), and hybrid OLAP (HOLAP) storage modes? Yes. Module 12: Working with Virtual Cubes v BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module Strategy Use the following strategy to present this module: ! Understanding Virtual Cubes Begin with a definition of virtual cubes and describe their characteristics. Discuss virtual cube limitations and storage. ! Obtaining Logical Results Explain that, when building a virtual cube from more than one source cube, students must follow some simple rules to obtain logical results. Explain that they need to use dimensions and measures that the source cubes have in common—otherwise there is no analytical value in combining the cubes. ! Building a Virtual Cube Introduce students to the Virtual Cube Wizard. While giving the lecture, open the Virtual Cube Wizard on your computer and show students the various interfaces. Describe the steps involved in creating a virtual cube— choosing the source cube, choosing the measures, choosing the dimensions, and finalizing the cube. ! Creating Calculated Members Explain that calculated members can be added to virtual cubes by using the Virtual Cube Editor. Describe the different ways to add calculated members to virtual cubes—creating calculated members and importing them. Module 12: Working with Virtual Cubes 1 BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Overview ! Understanding Virtual Cubes ! Obtaining Logical Results ! Building a Virtual Cube ! Creating Calculated Members A virtual cube is an online analytical processing (OLAP) cube that combines or extracts data from one or more source cubes. These cubes are called virtual because they consume no disk storage other than metadata. In this module, you will learn when to use virtual cubes and the mechanics of how to build them in Microsoft ® SQL Server ™ 2000 Analysis Services. After completing this module, you will be able to: ! Understand when to use virtual cubes and know their benefits. ! Know the rules for constructing meaningful virtual cubes. ! Build virtual cubes by using the Virtual Cube Wizard. ! Define calculated members in virtual cubes by using the Calculated Member Builder. Topic Objective To provide an overview of the module topics and objectives. Lead-in In this module, you will learn about virtual cubes and how to create them. 2 Module 12: Working with Virtual Cubes BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Understanding Virtual Cubes ! Virtual Cube Characteristics # Combine data from multiple cubes # Provide users with a subset of a single cube # Are used to limit user access to cube data ! Dimension Limitations # Cannot slice dimensions # Cannot include only some of a dimension’s levels ! Storage and Performance # Can include MOLAP, ROLAP, and HOLAP cubes # Provide endless cube flexibility A virtual cube is a cube that combines or extracts data from one or more source cubes. In many respects, a virtual cube is to Analysis Server what a view is to a relational database management system (RDBMS)—it provides a different view of the underlying data without storing any additional data except the metadata that defines the virtual cube. This module defines virtual cubes as being derived from source cubes. Source cubes are the cubes from which a virtual cube is derived. Virtual Cube Characteristics To users and applications, a virtual cube is simply a cube. It looks and behaves exactly like a source cube. A virtual cube can be used to: ! Combine data from two or more source cubes. For example, a cube containing sales data might be combined with a cube containing forecasts to measure actual sales versus forecast sales. If a virtual cube is based on more than one source cube, when the virtual cube is queried, it queries the source cubes in parallel. A virtual cube can combine up to 64 source cubes. ! Provide users with a subset of the dimensions and measures from a single source cube. This is useful when a source cube contains a great many measures and dimensions, and a group of users is interested in only a subset. ! Provide users with a subset of the dimensions and measures from a single source cube as a security measure. For instance, the source cube might contain a profit measure that certain users or groups of users are not allowed to see. Topic Objective To introduce the characteristics, limitations, and storage of virtual cubes. Lead-in A virtual cube combines or extracts data from one or more source cubes. In many respects, a virtual cube is to Analysis Server what a view is to a relational database management system (RDBMS). Note Note Module 12: Working with Virtual Cubes 3 BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY There is no limit to the number of virtual cubes that can be defined in a database. Dimension Limitations Following are limitations of virtual cubes: ! Virtual cubes cannot slice the dimensions of the source cubes. For example, suppose a source cube contains the dimension Region. If Region is placed in a virtual cube, the entire dimension is included. You cannot include only the Western region. ! You cannot choose which levels of the dimension are included. For example, you cannot include summary levels and exclude bottom-level members. The entire dimension, with all levels, must be included. The Measures dimension is an exception to these rules. You can pick the specific measures that populate a virtual cube. Storage and Performance Because virtual cubes consume no disk space, they rely on the underlying storage of the source cubes. Therefore: ! A single virtual cube can include multidimensional OLAP (MOLAP), relational OLAP (ROLAP), and hybrid OLAP (HOLAP) source cubes. ! Because a single source cube can contain MOLAP, ROLAP, and HOLAP partitions, there is endless flexibility in designing virtual cubes. Virtual cubes automatically use aggregations from the source cubes. The performance overhead imposed by the virtual cube on top of the source cubes is negligible. 4 Module 12: Working with Virtual Cubes BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Obtaining Logical Results When building a virtual cube based on more than one source cube, you must follow some simple rules to obtain logical results. Common dimensions and measures are required from source cubes: ! The source cubes should contain one or more shared dimensions that are the same, and at least one of the common shared dimensions should be included in the virtual cube. ! Analysis Manager does not enforce this rule, but the result will be nonsensical if it is not followed. This can be easily visualized from the preceding spreadsheet illustration. The first cube contains region and time dimensions. The second cube contains sales representatives and scenario dimensions. Because the two cubes have nothing in common, it makes no sense to base a virtual cube on them. There is no analytical value in combining cubes if they do not share a dimension. ! Include at least one measure from each source cube in the virtual cube or there is no reason to combine the cubes. Again, Analysis Manager will not prevent you from doing this. Topic Objective To explain the importance of using common measures and dimensions from the source cubes. Lead-in When building a virtual cube based on more than one source cube, you must follow some simple rules to obtain logical results. Delivery Tips Explain the preceding illustration by comparing two cubes with different dimensionality. Combining them into a virtual cube would produce nonsensical results. Note [...].. .Module 12: Working with Virtual Cubes 5 $ Building a Virtual Cube Topic Objective To go through the steps of creating a virtual cube Lead-in To create a virtual cube, you use the Virtual Cube Wizard ! Choosing the Source Cubes ! Choosing the Measures ! Choosing the Dimensions ! Finalizing the Virtual Cube You build a virtual cube simply by using the Virtual Cube Wizard To display... the wizard, right-click the Cubes folder and then click New Virtual Cube BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY 6 Module 12: Working with Virtual Cubes Choosing the Source Cubes Topic Objective To show how to choose source cubes for a virtual cube Lead-in The first step in creating a virtual cube is to select the source cube or cubes for the virtual cube Delivery Tip... PURPOSES ONLY 10 Module 12: Working with Virtual Cubes Lab A: Creating Virtual Cubes Topic Objective To introduce the lab Lead-in In this lab, you will create two virtual cubes You first will create a virtual cube as a subset of a source cube You will then create a virtual cube from two source cubes Explain the lab objectives Objectives After completing this lab, you will be able to: ! Create a virtual cube... cube ! Create a virtual cube from multiple source cubes Prerequisites Before working on this lab, you must have: ! Experience working with Analysis Manager ! An understanding of virtual cubes Estimated time to complete this lab: 10 minutes BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 12: Working with Virtual Cubes 11 Exercise 1 Creating the Basic Sales Virtual Cube In... all virtual dimensions defined in the source cubes A virtual dimension can be placed in a virtual cube The dimension from which it is derived will be placed in the virtual cube automatically You cannot include a virtual dimension in a virtual cube without also including the dimension on which it is based BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 12: Working with Virtual. .. used in regular cubes Working with the Virtual Cube Editor After you create a virtual cube, it appears in the list of cubes below the Cubes folder in Analysis Manager If you need to edit a virtual cube, right-click the cube and then click Edit The Virtual Cube Editor opens The Virtual Cube Editor is similar to the Cube Editor that you use to manage regular cubes ! Like the Cube Editor, the Virtual Cube... measure is not visible in the virtual cube The Visible property value of Count from the Sales cube persists in the virtual cube 6 Close the Virtual Cube Editor BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 12: Working with Virtual Cubes 19 Review Topic Objective To reinforce module objectives by reviewing key points ! Understanding Virtual Cubes Lead-in ! Obtaining Logical... in the Virtual Cube Editor, you use the Calculated Member Builder to define and edit the calculations BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 12: Working with Virtual Cubes 15 Importing Calculated Members As you modify a virtual cube, you can reuse calculations created in the source cubes You import the calculations into the virtual cube by using the Virtual. .. in a virtual cube ! Import a calculated member into a virtual cube Prerequisites Before working on this lab, you must have: ! Experience working with Analysis Manager ! An understanding of virtual cubes ! An understanding of calculated members ! Experience working with the Calculated Member Builder Lab Setup To complete this lab, you need the following: ! To have completed lab A, Creating Virtual Cubes, ... dialog box The Virtual Cube Wizard leaves you in the Virtual Cube Editor 2 Browse the cube data, and then close the Virtual Cube Editor BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 12: Working with Virtual Cubes 13 Exercise 2 Creating the Actual and Forecast Cube In this exercise, you will build a virtual cube combining the Sales and Sales Forecast cubes The Sales . the module topics and objectives. Lead-in In this module, you will learn about virtual cubes and how to create them. 2 Module 12: Working with Virtual. two cubes with different dimensionality. Combining them into a virtual cube would produce nonsensical results. Note Module 12: Working with Virtual