Tài liệu Expert Performance Indexing for SQL Sever 2012 pdf

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Tài liệu Expert Performance Indexing for SQL Sever 2012 pdf

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[...]... query needs to perform, resulting in an improvement in the performance of the query Another could be where the selectivity of a value is low compared to the number of rows in the table This could be an active status or shipped Boolean values; indexing on these values wouldn’t drastically improve performance, but filtering to just those records would provide a significant opportunity for query improvement... , …n ] ) ] Each of the options allows for different levels of control on the index creation process Table 1-1 provides a listing of all of the options available for CREATE INDEX In later chapters, examples and strategies for applying them are discussed More information on the CREATE INDEX syntax and examples of its use can be found in Books Online for SQL Server 2012 Table 1-1 CREATE INDEX Syntax Options... Pro Full-Text Search in SQL Server 2008, Pro SQL Server 2008 XML, Beginning Spatial with SQL Server 2008, and Pro Spatial with SQL Server 2012 You will finish this chapter with a deeper understanding of the fundamentals of index storage With this information, you’ll be better able to deal with, understand, and expect behaviors from the indexes in your databases Storage Basics SQL Server uses a number... in that it provides metadata information This page, though, provides metadata information for the database itself instead of for the data file There is one boot page per database and it is located on page 9 in the first data file for a database (see Figure 2-5) Some of information on the boot page includes the current version of the database, the create date and version for the database, the database... also included information on the metadata, or catalog views, available on indexes within SQL Server Each of the catalog views provides information on the structure and makeup of the index This information can assist in researching and understanding the view that are available The details in this chapter provide the framework for what will be discussed in later chapters By leveraging this information, you’ll... concepts discussed previously in this chapter For the sake of brevity, backward compatible features of the index DDL will not be discussed; information on those features can be found in Books Online for SQL Server 2012 XML and spatial indexes and full-text search will be discussed further in later chapters 7 CHAPTER 1 ■ Index Fundamentals Creating an Index Before an index can exist within your database,... pages, it will begin using uniform extents In a uniform extent, all pages in the extent are allocated to a single object in the database (see Figure 2-4) Due to this, pages for an object will be contiguous, which increases the number of pages of an object that can be read in a single read For more information on the benefits of contiguous reads, see Chapter 6 Figure 2-4 Uniform extent Page Types As mentioned,... you can search in Books Online Index Meta Data Before going too deep into indexing strategies, it is important to understand the information available in SQL Server on the indexes When there is a need to understand or know how an index is built, there are catalog views that can be queried to provide this information There are four catalog views available for indexes Every user and system database has... LOB pages required for the data and it will be stored on LOB pages instead (see Figure 2-6) Figure 2-6 Data page link to LOB page Organizing Pages So far you’ve looked at the low level components that make up the internals for indexing While these pieces are important to indexing, the structures in which these components are organized are where the value of indexing is realized SQL Server utilizes... available structure that can be used for indexing is the Balanced-tree, or B-tree, structure It is the most commonly used structure for organizing indexes in SQL Server and is used by both clustered and nonclustered indexes In a B-tree, pages are organized in a hierarchical tree structure, as shown in Figure 2-9 Within the structure, pages sorted to optimize searches for information within the structure . strategies for applying them are discussed. More information on the CREATE INDEX syntax and examples of its use can be found in Books Online for SQL Server 2012. Table. Full-Text Search in SQL Server 2008, Pro SQL Server 2008 XML, Beginning Spatial with SQL Server 2008, and Pro Spatial with SQL Server 2012. You will finish

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  • Expert Performance Indexing for SQL Server 2012

    • Contents at a Glance

    • Contents

    • About the Authors

    • About the Technical Reviewers

    • Acknowledgments

    • Introduction

    • Chapter 1: Index Fundamentals

      • Why Build Indexes?

      • Major Index Types

        • Heap Tables

        • Clustered Indexes

        • Nonclustered Indexes

        • Column Store Indexes

        • Other Index Types

          • XML Indexes

          • Spatial Indexes

          • Full-Text Search

          • Index Variations

            • Primary Key

            • Unique Index

            • Included Columns

            • Partitioned Indexes

            • Filtered Indexes

            • Compression and Indexing

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