What’s New in SQL Server System and Database Administration
System Administrator Responsibilities
System Databases
System Tables
System Views
System Stored Procedures
Summary
8 Installing SQL Server 2008
What’s New in Installing SQL Server 2008
Installation Requirements
Installation Walkthrough
Installing SQL Server Using a Configuration File
Installing Service Packs and Cumulative Updates
Slipstream Installations
Summary
9 Upgrading to SQL Server 2008
What’s New in Upgrading SQL Server
Using the SQL Server Upgrade Advisor (UA)
Destination: SQL Server 2008 or SQL Server 2008 R2
Upgrading Using a Configuration File
Slipstreaming Upgrades
Upgrading Other SQL Server Components
Summary
10 Client Installation and Configuration
What’s New in Client Installation and Configuration
Client/Server Networking Considerations
Client Installation
Client Configuration
Client Data Access Technologies
Summary
11 Security and User Administration
What’s New in Security and User Administration
An Overview of SQL Server Security
Authentication Methods
Managing Principals
Managing Securables
Managing Permissions
Managing SQL Server Logins
Managing SQL Server Users
Managing Database Roles
Managing SQL Server Permissions
The Execution Context
Summary
12 Data Encryption
What’s New in Data Encryption
An Overview of Data Security
An Overview of Data Encryption
SQL Server Key Management
Column-Level Encryption
Transparent Data Encryption
Column-Level Encryption Versus Transparent Data Encryption
Summary
13 Security and Compliance
Exposure and Risk
Across the Life Cycle
The Security Big Picture
Identity Access Management Components
Compliance and SQL Server
SQL Server Auditing
Setting Up Auditing via T-SQL
SQL Injection Is Easy to Do
Summary
14 Database Backup and Restore
What’s New in Database Backup and Restore
Developing a Backup and Restore Plan
Types of Backups
Recovery Models
Backup Devices
Backing Up a Database
Backing Up the Transaction Log
Backup Scenarios
Restoring Databases and Transaction Logs
Restore Scenarios
Additional Backup Considerations
Summary
15 Database Mail
What’s New in Database Mail
Setting Up Database Mail
Sending and Receiving with Database Mail
Using SQL Server Agent Mail
Related Views and Procedures
Summary
16 SQL Server Scheduling and Notification
What’s New in Scheduling and Notification
Configuring the SQL Server Agent
Viewing the SQL Server Agent Error Log
SQL Server Agent Security
Managing Operators
Managing Jobs
Managing Alerts
Scripting Jobs and Alerts
Multiserver Job Management
Event Forwarding
Summary
17 Administering SQL Server 2008 with PowerShell
What’s New with PowerShell
Overview of PowerShell
PowerShell Scripting Basics
PowerShell in SQL Server 2008
Step-By-Step Examples
Summary
18 SQL Server High Availability
What’s New in High Availability
What Is High Availability?
The Fundamentals of HA
Building Solutions with One or More HA Options
Other HA Techniques That Yield Great Results
High Availability from the Windows Server Family Side
Summary
19 Replication
What’s New in Data Replication
What Is Replication?
The Publisher, Distributor, and Subscriber Magazine Metaphor
Replication Scenarios
Subscriptions
Replication Agents
Planning for SQL Server Data Replication
SQL Server Replication Types
Basing the Replication Design on User Requirements
Setting Up Replication
Scripting Replication
Monitoring Replication
Summary
20 Database Mirroring
What’s New in Database Mirroring
What Is Database Mirroring?
Roles of the Database Mirroring Configuration
Setting Up and Configuring Database Mirroring
Testing Failover from the Principal to the Mirror
Client Setup and Configuration for Database Mirroring
Migrate to Database Mirroring 2008 as Fast as You Can
Using Replication and Database Mirroring Together
Using Database Snapshots from a Mirror for Reporting
Summary
21 SQL Server Clustering
What’s New in SQL Server Clustering
How Microsoft SQL Server Clustering Works
Installing SQL Server Clustering
Summary
22 Administering Policy-Based Management
Introduction to Policy-Based Management
Policy-Based Management Concepts
Implementing Policy-Based Management
Sample Templates and Real-World Examples
Policy-Based Management Best Practices
Summary
Part IV: Database Administration
23 Creating and Managing Databases
What’s New in Creating and Managing Databases
Data Storage in SQL Server
Database Files
Creating Databases
Setting Database Options
Managing Databases
Summary
24 Creating and Managing Tables
What’s New in SQL Server 2008
Creating Tables
Defining Columns
Defining Table Location
Defining Table Constraints
Modifying Tables
Dropping Tables
Using Partitioned Tables
Creating Temporary Tables
Summary
25 Creating and Managing Indexes
What’s New in Creating and Managing Indexes
Types of Indexes
Creating Indexes
Managing Indexes
Dropping Indexes
Online Indexing Operations
Indexes on Views
Summary
26 Implementing Data Integrity
What’s New in Data Integrity
Types of Data Integrity
Enforcing Data Integrity
Using Constraints
Rules
Defaults
Summary
27 Creating and Managing Views in SQL Server
What’s New in Creating and Managing Views
Definition of Views
Using Views
Creating Views
Managing Views
Data Modifications and Views
Partitioned Views
Indexed Views
Summary
28 Creating and Managing Stored Procedures
What’s New in Creating and Managing Stored Procedures
Advantages of Stored Procedures
Creating Stored Procedures
Executing Stored Procedures
Deferred Name Resolution
Viewing Stored Procedures
Modifying Stored Procedures
Using Input Parameters
Using Output Parameters
Returning Procedure Status
Debugging Stored Procedures Using SQL Server Management Studio
Using System Stored Procedures
Startup Procedures
Summary
29 Creating and Managing User-Defined Functions
What’s New in SQL Server 2008
Why Use User-Defined Functions?
Types of User-Defined Functions
Creating and Managing User-Defined Functions
Rewriting Stored Procedures as Functions
Creating and Using CLR Functions
Summary
30 Creating and Managing Triggers
What’s New in Creating and Managing Triggers
Using DML Triggers
Using DDL Triggers
Using CLR Triggers
Using Nested Triggers
Using Recursive Triggers
Summary
31 Transaction Management and the Transaction Log
What’s New in Transaction Management
What Is a Transaction?
How SQL Server Manages Transactions
Defining Transactions
Transactions and Batches
Transactions and Stored Procedures
Transactions and Triggers
Transactions and Locking
Coding Effective Transactions
Transaction Logging and the Recovery Process
Long-Running Transactions
Bound Connections
Distributed Transactions
Summary
32 Database Snapshots
What’s New with Database Snapshots
What Are Database Snapshots?
Limitations and Restrictions of Database Snapshots
Copy-on-Write Technology
When to Use Database Snapshots
Setup and Breakdown of a Database Snapshot
Reverting to a Database Snapshot for Recovery
Setting Up Snapshots Against a Database Mirror
Database Snapshots Maintenance and Security Considerations
Summary
33 Database Maintenance
What’s New in Database Maintenance
The Maintenance Plan Wizard
Managing Maintenance Plans Without the Wizard
Executing a Maintenance Plan
Maintenance Without a Maintenance Plan
Database Maintenance Policies
Summary
Part V: SQL Server Performance and Optimization
34 Data Structures, Indexes, and Performance
What’s New for Data Structures, Indexes, and Performance
Understanding Data Structures
Database Files and Filegroups
Database Pages
Space Allocation Structures
Data Compression
Understanding Table Structures
Understanding Index Structures
Data Modification and Performance
Index Utilization
Index Selection
Evaluating Index Usefulness
Index Statistics
SQL Server Index Maintenance
Index Design Guidelines
Indexed Views
Indexes on Computed Columns
Filtered Indexes and Statistics
Choosing Indexes: Query Versus Update Performance
Identifying Missing Indexes
Identifying Unused Indexes
Summary
35 Understanding Query Optimization
What’s New in Query Optimization
What Is the Query Optimizer?
Query Compilation and Optimization
Query Analysis
Row Estimation and Index Selection
Join Selection
Execution Plan Selection
Query Plan Caching
Other Query Processing Strategies
Parallel Query Processing
Common Query Optimization Problems
Managing the Optimizer
Summary
36 Query Analysis
What’s New in Query Analysis
Query Analysis in SSMS
SSMS Client Statistics
Using the SET SHOWPLAN Options
Using sys.dm_exec_query_plan
Query Statistics
Query Analysis with SQL Server Profiler
Summary
37 Locking and Performance
What’s New in Locking and Performance
The Need for Locking
Transaction Isolation Levels in SQL Server
The Lock Manager
Monitoring Lock Activity in SQL Server
SQL Server Lock Types
SQL Server Lock Granularity
Lock Compatibility
Locking Contention and Deadlocks
Table Hints for Locking
Optimistic Locking
Summary
38 Database Design and Performance
What’s New in Database Design and Performance
Basic Tenets of Designing for Performance
Logical Database Design Issues
Denormalizing a Database
Database Filegroups and Performance
RAID Technology
SQL Server and SAN Technology
Summary
39 Monitoring SQL Server Performance
What’s New in Monitoring SQL Server Performance
Performance Monitoring Tools
A Performance Monitoring Approach
Summary
40 Managing Workloads with the Resource Governor
Overview of Resource Governor
Resource Governor Components
Configuring Resource Governor
Monitoring Resource Usage
Modifying Your Resource Governor Configuration
Summary
41 A Performance and Tuning Methodology
The Full Architectural Landscape
Primary Performance and Tuning Handles
A Performance and Tuning Methodology
Performance and Tuning Design Guidelines
Tools of the Performance and Tuning Trade
Summary
Part VI: SQL Server Application Development
42 What’s New for Transact-SQL in SQL Server 2008
MERGE Statement
Insert over DML
GROUP BY Clause Enhancements
Variable Assignment in DECLARE Statement
Compound Assignment Operators
Row Constructors
New date and time Data Types and Functions
Table-Valued Parameters
Hierarchyid Data Type
Using FILESTREAM Storage
Sparse Columns
Spatial Data Types
Change Data Capture
Change Tracking
Summary
43 Transact-SQL Programming Guidelines, Tips, and Tricks
General T-SQL Coding Recommendations
General T-SQL Performance Recommendations
T-SQL Tips and Tricks
In Case You Missed It: New Transact-SQL Features in SQL Server 2005
The xml Data Type
The max Specifier
TOP Enhancements
The OUTPUT Clause
Common Table Expressions
Ranking Functions
PIVOT and UNPIVOT
The APPLY Operator
TRY...CATCH Logic for Error Handling
The TABLESAMPLE Clause
Summary
44 Advanced Stored Procedure Programming and Optimization
T-SQL Stored Procedure Coding Guidelines
Using Cursors in Stored Procedures
Nested Stored Procedures
Using Temporary Tables in Stored Procedures
Using Remote Stored Procedures
Stored Procedure Performance
Using Dynamic SQL in Stored Procedures
Installing and Using .NET CLR Stored Procedures
Using Extended Stored Procedures
Summary
45 SQL Server and the .NET Framework
What’s New in SQL Server 2008 and the .NET Framework
Getting Comfortable with ADO.NET 3.5 and SQL Server 2008
Developing with LINQ to SQL
Using ADO.NET Data Services
Leveraging the Microsoft Sync Framework
Summary
46 SQLCLR: Developing SQL Server Objects in .NET
What’s New for SQLCLR in SQL Server 2008
Developing Custom Managed Database Objects
Summary
47 Using XML in SQL Server 2008
What’s New in Using XML in SQL Server 2008
Understanding XML
Relational Data As XML: The FOR XML Modes
XML As Relational Data: Using OPENXML
Using the xml Data Type
Indexing and Full-Text Indexing of xml Columns
Summary
48 SQL Server Web Services
What’s New in SQL Server Web Services
Web Services Migration Path
Web Services History and Overview
Building Web Services
Examples: A C# Client Application
Using Catalog Views and System Stored Procedures
Controlling Access Permissions
Summary
49 SQL Server Service Broker
What’s New in Service Broker
Understanding Distributed Messaging
Designing a Sample System
Understanding Service Broker Constructs
Service Broker Routing and Security
Troubleshooting SSB Applications with ssbdiagnose.exe
Related System Catalogs
Summary
50 SQL Server Full-Text Search
What’s New in SQL Server 2008 Full-Text Search
Upgrade Options in SQL Server 2008
How SQL Server FTS Works
Implementing SQL Server 2008 Full-Text Catalogs
Setting Up a Full-Text Index
Full-Text Searches
Full-Text Search Maintenance
Full-Text Search Performance
Full-Text Search Troubleshooting
Summary
Part VII: SQL Server Business Intelligence Features
51 SQL Server 2008 Analysis Services
What’s New in SSAS
Understanding SSAS and OLAP
Understanding the SSAS Environment Wizards
An Analytics Design Methodology
An OLAP Requirements Example: CompSales International
Summary
52 SQL Server Integration Services
What’s New with SSIS
SSIS Basics
SSIS Architecture and Concepts
SSIS Tools and Utilities
A Data Transformation Requirement
Running the SSIS Wizard
The SSIS Designer
The Package Execution Utility
Connection Projects in Visual Studio
Change Data Capture Addition with R2
Using bcp
Logged and Nonlogged Operations
Summary
53 SQL Server 2008 Reporting Services
What’s New in SSRS 2008
Reporting Services Architecture
Installing and Configuring SSRS
Developing Reports
Management and Security
Performance and Monitoring
Summary
Part VIII: Bonus Chapters
54 Managing Linked and Remote Servers
What’s New in Managing Linked and Remote Servers
Managing Remote Servers
Linked Servers
Adding, Dropping, and Configuring Linked Servers
Mapping Local Logins to Logins on Linked Servers
Obtaining General Information About Linked Servers
Executing a Stored Procedure via a Linked Server
Setting Up Linked Servers Using SQL Server Management Studio
Summary
55 Configuring, Tuning, and Optimizing SQL Server Options
What’s New in Configuring, Tuning, and Optimizing SQL Server Options
SQL Server Instance Architecture
Configuration Options
Fixing an Incorrect Option Setting
Setting Configuration Options with SSMS
Obsolete Configuration Options
Configuration Options and Performance
Database Engine Tuning Advisor
Data Collection Sets
Summary
56 SQL Server Disaster Recovery Planning
What’s New in SQL Server Disaster Recovery Planning
How to Approach Disaster Recovery
Microsoft SQL Server Options for Disaster Recovery
The Overall Disaster Recovery Process
Have You Detached a Database Recently?
Third-Party Disaster Recovery Alternatives
Summary
Index
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Nội dung
ptg 1084 CHAPTER 33 Database Maintenance Managing Maintenance Plans Without the Wizard You can create or modify maintenance plans in SQL Server 2008 without using the Maintenance Plan Wizard. To create a new maintenance plan without the wizard, you right-click the Maintenance Plan node in the Object Explorer and select New Maintenance Plan. You are prompted for a maintenance plan name and then taken to the Design tab for the maintenance plan. The Design tab consists of a properties section at the top of the screen and a plan designer surface that is empty for a new maintenance plan. Existing maintenance plans are displayed in the Design tab when you right-click the plan and select Modify. Figure 33.13 shows the Design tab for a maintenance plan that was created with the Maintenance Plan Wizard to back up the system databases. The Design tab represents a significant difference from the way maintenance plans were managed in SQL Server 2000. The plan designer surface on the Design tab has drag-and- drop capabilities that allow you to add maintenance tasks to your plan. The available tasks are located in the Toolbox component. The Toolbox and the related tasks are shown in Figure 33.13 in the middle portion of the screen. To add a tool from the Toolbox, you drag the item from the Toolbox to the plan designer surface. Alternatively, you can double-click the task, and the task appears on the plan designer surface. FIGURE 33.13 The maintenance plan Design tab. Download from www.wowebook.com ptg 1085 Managing Maintenance Plans Without the Wizard 33 On the plan designer surface, you can move each of the tasks around, link them to other tasks, and edit them by double-clicking them. You can also right-click a task to edit it, group it with other tasks, autosize it, and gain access to other task options. You can right- click an empty section of the plan designer surface to add annotations or comments that provide additional information about the task or the overall plan. NOTE The dialog boxes displayed when you edit a task are unique for each task. The avail- able maintenance plan tasks display an options screen like the one displayed during the execution of the Maintenance Plan Wizard. This provides consistency that is in place regardless of where the task is defined. Adding a task to an existing maintenance plan is a good starting point to become familiar with the workings of the Design tab. Consider, for example, the maintenance plan shown in Figure 33.13. This plan, which was initially created with the Maintenance Plan Wizard, is used to create full database backups of all the system databases. One critical aspect that is missing from this plan is a task to remove older database backups. The task that can help you with this is the Maintenance Cleanup task. If you double-click that task in the Toolbox, the task is added to the plan designer surface, as shown in Figure 33.14. FIGURE 33.14 Adding a task to the plan designer surface. Download from www.wowebook.com ptg 1086 CHAPTER 33 Database Maintenance After you add a task to the plan designer surface, you need to configure it. Note that a small red X icon appears on the right side of the task if the task has not yet been config- ured. To configure the Maintenance Cleanup task, you double-click it on the plan designer surface. Figure 33.15 shows the screen that appears so you can configure the Maintenance Cleanup task. You can use the Maintenance Cleanup task to clean up old backup files or maintenance plan text reports. The deletion of older backup files is particularly important because data- base backups tend to be large files and can use up a significant amount of disk space. The File Location section of the screen enables you to delete a specific file, or you can delete files in a folder based on search criteria. In most cases, you want to search the folder to delete older files. When cleaning up database backup files, you typically specify the file extension .bak. If you chose to write each database’s backups to a separate folder, you should choose the Include First-Level Subfolders options, which allows you to search all first-level subfolders that exist under the folder specified. This simplifies the cleanup process and eliminates the need to have a separate cleanup task for each subfolder. In the last section of the configuration screen for the Maintenance Cleanup task, you specify how old a file must be in order to be deleted. The default is four weeks, but you FIGURE 33.15 Configuring the Maintenance Cleanup task. Download from www.wowebook.com ptg 1087 Managing Maintenance Plans Without the Wizard 33 can adjust this setting to the desired time frame by using the related drop-downs. If you uncheck Delete Files Based on the Age of the File at Task Run Time, all files in the folder or subfolders are deleted, regardless of age. NOTE The deletion of database backup files is not based on the file dates or the name of the backup file. The Maintenance Cleanup task uses a procedure named xp_delete_file that examines the database backup and time the backup was created. Renaming the database backup file does not affect its inclusion in the deletion process. After configuring the options for the Maintenance Cleanup task, you can click the View T- SQL button at the bottom of the screen. This feature reveals what is going on behind the scenes when the plan executes. Prior to SQL Server 2005, you had to obtain this kind of information by using the Profiler. When you click OK, the task is ready to use in the maintenance plan. The task runs in parallel with the other tasks defined in the plan unless a precedence or link is established between the tasks. To establish a link between the tasks, you select the first task that you want to execute. When the task is selected, a green arrow is shown at the bottom of the task’s box in the plan designer surface. You click the green arrow and drag it to the task that you want to run next. The green arrow is then connected to the other task. If you double-click the green arrow (or right-click and choose Edit), the Precedence Constraint Editor appears, as shown in Figure 33.16. The paragraph at the top of the Precedence Constraint Editor gives a good description of what a precedence constraint is. In short, it can link tasks together based on the results of their execution. For example, if a backup database task succeeds, a Maintenance Cleanup FIGURE 33.16 The Precedence Constraint Editor. Download from www.wowebook.com ptg 1088 CHAPTER 33 Database Maintenance task can be defined to run next. You can also set the constraint value so that the next task will run only if the first task fails, or you can have the next task run based on the prior task’s completion, regardless of whether if succeeds or fails. In addition, you can link multiple tasks together with precedence. You define the logical relationship between tasks in the Multiple Constraints section of the Precedence Constraint Editor. The workflow and relationships that can be defined between tasks for a maintenance plan are extensive and beyond the scope of this chapter. Many of the workflow concepts are similar to those of the DTS designer in SQL Server 2000 and the SSIS designer in SQL Server 2008. Executing a Maintenance Plan Maintenance plans that have been scheduled run automatically according to the schedule defined. You can also run maintenance plans manually by right-clicking a maintenance plan and selecting Execute or by selecting the SQL Server Agent job associated with the maintenance plan and starting the job. The execution behavior is different, depending on the means you use. If you choose to run the maintenance plan from the Management node, the SSIS package is launched, and the Execute Maintenance Plan window displays the current status of the plan execution. If you run the SQL Server Agent job to execute the maintenance plan, a dialog box indi- cating the execution status of the job appears. The dialog does not indicate success for the maintenance plan until the entire maintenance plan has completed. The dialog box for the job can be closed, and the job will still continue to run. The Execute Maintenance Plan window, on the other hand, does not have an option to close it, and it must stay open until the plan completes. There are two other means for monitoring the execution of maintenance plans. The Job Activity Monitor shows a status of executing while a maintenance plan is executing. You can set the refresh settings on the Job Activity Monitor to auto-refresh for the desired increment. You can also monitor the execution by establishing a connection to the SSIS server in SSMS. To establish an SSIS connection in SSMS, you click the Connect drop- down in the Object Explorer and choose Integration Services. Figure 33.17 shows an example of the Object Explorer with an Integration Services connection. The Integration Services connection in the Object Explorer shows the packages that are running in addition to the packages that have been created. If you expand the Stored Packages node and navigate to the MSDB node, you see a node named Maintenance Plans that shows all the SSIS packages that have been created. You can also edit the package with BIDS, but that topic is beyond the scope of this chapter. See Chapter 52 for more information. Download from www.wowebook.com ptg 1089 Maintenance Without a Maintenance Plan 33 FIGURE 33.17 The Object Explorer with an Integration Services connection. NOTE SSIS does not need to be installed on the SQL Server machine to be able to create and execute maintenance plans. In the initial release of SQL Server 2005, this was a requirement but was changed with SQL Server 2005 SP2. This change carried over to SQL Server 2008, and maintenance plans are now fully functional with the SQL Server Database Services installation. Maintenance Without a Maintenance Plan You can perform database maintenance without the use of the built-in maintenance plans that come with SQL Server. The additional complexity in SQL Server 2008 may steer some people away from the use of these plans. In addition, these plans cannot be scripted, so deployment to multiple environments is not straightforward. Database maintenance that is performed without a maintenance plan is often performed using custom scripts or stored procedures that execute the T-SQL commands to perform the maintenance. Other methods include manually executing the SQLMAINT utility to perform various maintenance tasks such as database backups and consistency checks. Often these maintenance commands or custom scripts are then scheduled to run on a regular basis by manually setting up jobs within the SQL Server Agent job scheduler in SQL Server Management Studio. (For more information on setting up and scheduling jobs in SQL Server Agent, see Chapter 16, “SQL Server Scheduling and Notification.”) Setting up maintenance tasks manually is a viable option, especially for the more experi- enced DBA because it requires additional development work and familiarity with the maintenance commands and options. However, even the experienced DBA should consider using maintenance plans because maintenance tasks set up manually may lack the integration with other SQL Server components that is offered with the SQL Server 2008 maintenance plans. Download from www.wowebook.com ptg 1090 CHAPTER 33 Database Maintenance Database Maintenance Policies Policy-Based Management, a new management feature introduced in SQL Server 2008, allows you to manage your SQL Server instances through clearly defined policies, reducing the potential for administrative errors or oversight. The policy-based framework imple- ments the policies you defined via a Policy Engine, SQL Server Agent jobs, SQLCLR, DDL triggers, and Service Broker. You can choose to have the policies you defined be applied or evaluated against a single server or a group of servers, thus improving the scalability of monitoring and administration. Policy-Based Management allows you to prescribe the way you want your databases main- tained, and the system will help ensure things stay that way. Essentially, Policy-Based Management allows you to define rules for one or more SQL Servers and evaluate them. The goal of this feature is to make it easier for you to manage one or more servers by noti- fying you when servers are out of compliance with the database maintenance policies you have defined. For example, you could define a policy to ensure that transaction log backups are being performed on the appropriate intervals on your OLTP databases. Policy-Based Management allows you to determine when one of your databases is not in compliance with your log backup policy. You can set up this policy to be evaluated on demand or via a schedule. For more information on defining and using policies, see Chapter 22. Summary Establishing a database maintenance plan is important. Just like your car or your home, a database needs maintenance to keep working properly. The powerful features available with the SQL Server 2008 maintenance plans and Maintenance Plan Wizard make the creation of a robust maintenance plan relatively easy. If you establish your maintenance plans early in the life of your databases, you will save yourself time and aggravation in the long run. Chapter 34 delves further into the importance of indexes and their relationship to perfor- mance. It expands on the optimization of indexes mentioned in this chapter and describes the role that indexes play in keeping databases running fast. Download from www.wowebook.com ptg CHAPTER 34 Data Structures, Indexes, and Performance IN THIS CHAPTER . What’s New for Data Structures, Indexes, and Performance . Understanding Data Structures . Database Files and Filegroups . Database Pages . Understanding Table Structures . Understanding Index Structures . Data Modification and Performance . Index Utilization . Index Selection . Evaluating Index Usefulness . Index Statistics . SQL Server Index Maintenance . Index Design Guidelines . Indexed Views . Indexes on Computed Columns . Filtered Indexes and Statistics . Choosing Indexes: Query Versus Update Performance . Identifying Missing Indexes . Identifying Unused Indexes A number of factors affect SQL Server performance. One of the key factors is your table and index design; poor table and index design can result in excessive I/O and poor performance. To aid in developing a good table and index design in an effort to improve SQL Server performance by minimizing I/O, you need to have a good understanding of SQL Server data structures and indexes. Proper table and index design is a key issue in achieving optimum SQL Server application performance. For example, you can often realize substantial performance gains in your SQL Server applications by creating the proper indexes to support the queries and operations being performed. At the same time, it’s important to keep in mind that although many indexes on a table can help improve response time for queries and reports, too many indexes can hurt the performance of inserts, updates, and deletes due to the overhead required to maintain the index and data rows. Additionally, other index design decisions, such as which column(s) to create a clustered index on, might be influ- enced as much by how the data is inserted and modified and what the possible locking implications might be as they are by the query response time alone. In this chapter, you learn about the underlying structures of databases, tables, rows, and indexes and how SQL Server maintains index and data structures because this informa- tion provides a basis for understanding the performance of your tables and indexes. This chapter discusses the storage structures in SQL Server and how these storage structures are maintained and managed. The chapter also discusses how SQL Server evaluates and uses indexes to improve query response time. Using this information, you should have a better understanding of the issues and factors that influence good table and index design. Download from www.wowebook.com ptg 1092 CHAPTER 34 Data Structures, Indexes, and Performance What’s New for Data Structures, Indexes, and Performance SQL Server 2008 provides a number of new features related to data structures, indexes, and performance. Among these new features are filtered indexes and statistics. Filtered indexes utilize a WHERE clause that filters or limits the number of rows included in the index. The smaller filtered index allows queries run against rows containing data values in the index to run faster. These filtered indexes can also save on the disk space used by the index. A well-designed filtered index can improve query performance, reduce index maintenance costs, and reduce index storage costs compared with full-table indexes. Also new to SQL Server 2008 is the capability to compress data in indexes and tables to reduce the amount of storage space required and, in turn, reduce the I/O needed for these objects. Page-level data compression helps to reduce both storage and memory requirements as the data is compressed both on disk and when brought into the SQL Server data cache. Row-level compression isn’t true data compression but implements a more efficient storage format for fixed-length data. Other storage features introduced in SQL Server 2008 to reduce storage space requirements are sparse columns and column sets. Sparse columns are ordinary columns that use an opti- mized storage format for NULL values. FILESTREAM storage was also introduced in SQL Server 2008 as a new storage mechanism for binary large object (BLOB) data. FILESTREAM storage is a property that can be applied to varbinary(max) columns and enables SQL Server applications to store unstructured data, such as documents and images, directly in the NTFS file system while still maintain- ing the behavior of a database column. The advantages of FILESTREAM storage are improved performance and increased size of BLOB data, expanding from the 2GB limit of image columns to the available space in the file system. Spatial indexes are new to SQL Server 2008 as well. These indexes are used against spatial data defined by coordinates of latitude and longitude. The spatial data is essential for effi- cient global navigation. The spatial indexes are grid-based and help optimize the perfor- mance of searches against the spatial data. NOTE This chapter assumes that you already have an understanding of the different types of indexes and how to define them. For more information on index types and how to cre- ate indexes, see Chapter 25, “Creating and Managing Indexes.” Download from www.wowebook.com ptg 1093 Database Files and Filegroups 34 Understanding Data Structures SQL Server DBAs and users do not see data and storage the same way SQL Server does. A DBA or end user sees a database more logically as the following: . Databases, physically stored in files . Tables and indexes, placed in filegroups within databases . Rows, stored in tables SQL Server internally sees these storage structures at a lower, physical level as . Databases, physically stored in data and log files . Pages within these files, allocated to tables and indexes . Data and index rows, stored in slots on pages Database Files and Filegroups Databases in SQL Server 2008 span at least two, and optionally several, database files. There must always be at least one file for data and one file for the transaction log. These database files are normal operating system files created in a directory within the operating system. These files are created when the database is created or when a database is expanded. Each database file has the following set of properties: . A logical filename—This name is used for internal reference to the file. . A physical filename—This name is the actual physical pathname of the file. . An initial size—If no size is specified for primary data file, its initial size, by default, is the minimum size required to hold the contents of the model database. . An optional maximum size—A maximum file size limit can be specified. . A file growth increment—This amount is specified in megabytes or as a percentage. The information and properties about each file for a database are stored in the database visible via the system catalog view called sys.database_files. This view exists in every database and contains information about each of the database files. The master database contains a similar view, sys.master_files, that contains file information for all databases within the SQL Server instance. Table 34.1 lists the most useful columns in the sys.database_files view. Download from www.wowebook.com . jobs within the SQL Server Agent job scheduler in SQL Server Management Studio. (For more information on setting up and scheduling jobs in SQL Server Agent, see Chapter 16, SQL Server Scheduling. installed on the SQL Server machine to be able to create and execute maintenance plans. In the initial release of SQL Server 2005, this was a requirement but was changed with SQL Server 2005 SP2 changed with SQL Server 2005 SP2. This change carried over to SQL Server 2008, and maintenance plans are now fully functional with the SQL Server Database Services installation. Maintenance Without