Hướng dẫn học Microsoft SQL Server 2008 part 105 ppsx

Planning database maintenance Database maintenance plans include the following routine tasks: ■ Checking database integrity ■ Performing index maintenance ■ Updating database statistics

■ DBCC dllname FREE): Unloads the specified dll from memory

■ DBCC MEMORYSTATUS: Provides a snapshot of the current memory status of SQL Server

This command is very useful in troubleshooting issues that relate to SQL Server memory consumption

■ DBCC USEROPTIONS: Returns the activeSEToptions for the current connections The following three DBCC commands are used with trace flags Trace flags are used temporarily to set

certain specific SQL Server characteristics or turn off some behavior For example, trace flag 1204 is

used to enabled deadlock reporting to SQL Server ErrorLog

■ DBCC TRACEON: Turns on the specified trace flags

■ DBCC TRACEOFF: Turns off the specified trace flags

■ DBCC TRACESTATUS: Displays the active trace flags

Managing Database Maintenance

SQL Server provides a host of database maintenance commands Fortunately, it also provides the DBA

with ways to schedule maintenance tasks

Planning database maintenance

Database maintenance plans include the following routine tasks:

■ Checking database integrity

■ Performing index maintenance

■ Updating database statistics

■ Performing database backups

■ Shrinking the database

■ Checking file sizes and free disk space These maintenance tasks can be automated and scheduled using the SQL Server Agent service The

maintenance tasks are referred to as SQL Server Agent jobs

Maintenance plan

There are two ways to create a maintenance plan:

■ Maintenance Plan Wizard: Used to quickly create a basic maintenance plan, this wizard enables you to choose typical predefined maintenance tasks such as performing database backup, rebuilding indexes, updating statistics, checking data integrity, and shrinking the database It does not allow you to add any custom tasks

■ Maintenance Plan Design Surface: Used for designing maintenance plans with more flexi-bility, this option enables you to create a workflow of typical maintenance tasks and custom maintenance tasks using T-SQL scripts It also allows extended logging, which can be very useful for troubleshooting purposes

All of the maintenance plans appear in theManagement\Maintenance Plansfolder of SQL Server

Management Studio To launch the Maintenance Plan Wizard, right-click theMaintenance Plans

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folder and choose Maintenance Plan Wizard Follow the simple step-by-step wizard to create the

maintenance plan

To launch the Maintenance Plan Design Surface, right-click theMaintenance Plansfolder and

choose New Maintenance Plan from the context menu Type a name for the maintenance plan in the

New Maintenance Plan dialog and click OK

Once you assign a name to your maintenance plan, Management Studio opens a new window that

includes the maintenance plan name, a description, the time you want to schedule the maintenance

plan, and a list of tasks to perform Figure 42-1 shows a sample maintenance plan with some tasks

already entered

Adding a task

A maintenance plan must contain at least one task Fortunately, it isn’t difficult to add one Simply drag

and drop the appropriate task from the Toolbox, shown in Figure 42-2, to the design area of the

main-tenance plan The resulting task will appear as a square (refer to Figure 42-1)

FIGURE 42-1

Create a maintenance plan by adding some tasks and scheduling a time to perform the tasks

FIGURE 42-2

Use the Toolbox to add new tasks to your maintenance plan

FIGURE 42-3

Define the task specifics using the Properties window

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The task isn’t configured yet Use the Properties window, shown in Figure 42-3, to configure the task.

The content of the Properties window varies by task For example, when you select Back Up Database

Task, you’ll see properties for choosing the kind of database, the backup device type, and other

infor-mation associated with backing up the database The upper portion of the Properties window contains

the name of the selected task You can choose other tasks using the drop-down list box The middle of

the Properties window contains a list of properties for the selected task You can organize the

proper-ties by category or in alphabetical order The lower part of the Properproper-ties window contains a description

for the selected property Once you have worked with tasks for a while, the description usually provides

enough information to help you remember how to use the selected property

Sometimes you may not want to use the Properties window For example, you might be working with a

new task In this case, you can bypass the Properties window by double-clicking the task A task-specific

window like the one shown in Figure 42-4 for a backup task will appear Unlike the Properties window,

this dialog displays the task properties in context In addition, it grays out task elements until you define

the correct functionality For example, when you choose to back up specific databases, the dialog won’t

let you perform any other configuration task until you choose one or more databases for the backup

FIGURE 42-4

In addition to the Properties window, you can use the task-related dialog for configuration

It’s interesting to click View T-SQL when you finish configuring the task The resulting window, like the

one shown in Figure 42-5, displays the T-SQL that the task will use The Transact SQL (Task

Gener-ated) window won’t let you edit the command, but seeing how the Maintenance Plan Wizard generates

the code can prove helpful when you need to create T-SQL commands of your own

FIGURE 42-5

The View T-SQL button enables you to see the Transact SQL command

You know when a task is complete by the appearance of the square in the design area Incomplete tasks,

those that won’t execute correctly, display a red circle with an X through it on the right side of the

window

After you define a task, add the next task in your list You can add the tasks in any order and place

them in any order onscreen Connect the tasks in the order in which you want SQL Server to

exe-cute them Figure 42-1 showed two tasks, with one task connected to the next task in the list In

that example, first the integrity of theAdventureWorks2008database is checked, and then it is

backed up

Defining the schedule

You can perform tasks on demand or schedule them to run automatically Generally, it’s a good idea to

set standard tasks such as backup to run automatically Click the ellipses next to the Schedule field to

display the Job Schedule Properties dialog, shown in Figure 42-6, when you want to change the task

schedule

Select the scheduling requirements for the task For example, you can set a task to run daily, weekly, or

monthly The dialog also enables you to select a specific starting time for the task and determine when

the scheduling begins and ends

The one form of scheduling that this dialog doesn’t provide is on demand To set the maintenance task

to run on demand, simply leave the Job Schedule Properties empty

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FIGURE 42-6

Define a schedule that meets the task requirements; use off-hours scheduling for resource-intensive

tasks

Creating new connections

Depending on your database setup, you might need to create multiple connections to perform a

particular task The maintenance plan always provides a connection to the default instance of the local

database Click Manage Connections to add more connections to the current maintenance plan (any

additions won’t affect other maintenance plans you create) The Manage Connections dialog shown in

Figure 42-7 will appear

Click Add in the Manage Connections dialog to add a new connection The New Connection dialog will

appear A connection consists of three elements: connection name, server name, and server security

Choose a connection name that reflects the server and instance Using a name such as ‘‘My Connection’’

won’t be particularly helpful when you need to troubleshoot the maintenance task later You can either

type the server and instance name or select it from a list that the maintenance plan provides when you

click the ellipses next to the Select or Enter a Server Name field Finally, choose between Windows

integrated or SQL Server security Click OK to add the new connection to the list

FIGURE 42-7

Add new connections as needed to perform maintenance tasks

The Manage Connections dialog also enables you to edit existing connections or remove old connections

When you edit an existing connection, you see a New Connection dialog in which you can change the

logon arguments or the server name for the connection The dialog grays out the other fields Simply

click Remove to delete a connection you no longer need from the list

Connection deletion is a one-way process, and it happens quite quickly Make sure you have the correct connection selected before you click Remove because the maintenance plan won’t ask for confirmation before deleting the connection.

Logging the maintenance progress

Many of the maintenance tasks that you automate will execute during off hours, when you’re unlikely

to be around to monitor the system Fortunately, you can set maintenance tasks to log and report their

actions so that you don’t need to watch them every moment To use this feature, click the Reporting

and Logging icon next to the Manage Connections icon The Reporting and Logging dialog shown in

Figure 42-8 will appear

The Reporting and Logging dialog includes an option that enables you to send the report to a file or

your e-mail The e-mail feature is quite handy and saves you the time of searching for the file on the

hard drive Conversely, the text file provides an archive that could prove helpful long after you’ve

deleted the e-mail from your inbox Once you configure the reporting options, click OK, and the

maintenance plan will record its actions for you

Best Practice

You normally want to provide extended information about all maintenance tasks that the system performs

without your supervision Even the smallest piece of information can help you determine where a

particular maintenance action went awry

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FIGURE 42-8

Use the Reporting and Logging dialog to monitor your maintenance tasks

Command-line maintenance

Database maintenance is normally performed within SQL Server Management Studio or automated with

SQL Server Agent, but maintenance can be performed from the DOS command prompt by means of the

SQLMaintutility This utility has numerous options that can perform backups, update statistics, and

runDBCC

This feature will be removed in the next version of SQL Server Do not use this feature in

new development work, and plan to change applications that use this feature To run SQL

Server maintenance plans from the command line, use the dtexec utility.

Specific information onSQLMaintanddtexeccan be found in SQL Server 2008 Books Online

Monitoring database maintenance

It’s not enough to simply schedule tasks; they must be monitored as well In larger installations with

dozens of SQL Servers spread around the globe, monitoring the health of SQL Server and the databases

is itself a full-time job Table 42-1 provides a sample DBA daily checklist that can be used as a starting

point for developing a database monitoring plan

TABLE 42-1

DBA Daily Checklist

System Databases Backup

Production User Databases Backup

SQL Agent, SQL Maint, & DTC Running

Database Size, Growth, Disk Free Space

Batch Jobs Execute OK

DBCC Jobs Execute OK

SQL Log Errors

Replication Log Agent Running

Replication Distribution Cleanup Job Execute OK

SQL Server Last Reboot

Depending on the number of servers and the complexity, the DBA daily checklist can be maintained

manually with an Excel spreadsheet or tracked in a SQL Server table

Summary

This chapter covered database maintenance in detail SQL Server offers a rich set of commands and

utilities that can be used to monitor the health of, and perform maintenance on, SQL Server The

Maintenance Plan Wizard is also available to streamline database maintenance All installations of SQL

Server should also include a database maintenance schedule to assist the DBA in keeping track of

maintenance performed

The next chapter explains how to use SQL Server Agent, which may be used to schedule jobs and create

custom maintenance jobs, and SQL Server Database Mail, for sending e-mail from SQL Server

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Automating Database

Maintenance with SQL

Server Agent

IN THIS CHAPTER

Setting up SQL Server Agent Understanding alerts, operators, and jobs Managing alerts Managing operators Managing jobs Setting up Database Mail

The automation of database maintenance is crucial to ensuring that a

database is regularly checked, maintained, and optimized Automated

checking consists of monitoring database size to identify issues before

they generate mayhem; maintenance includes frequent backups; and optimization

involves tweaking the index configuration for optimal performance Automation

ensures that these activities do not consume too much of your time, so you can

focus on more pressing issues (such as improving your golf game, perhaps)

Ideally, SQL Server can monitor itself and send alerts when it encounters a

crit-ical condition Luckily Microsoft grants this specific wish, because SQL Server

includes a powerful component that can send alerts when specific critical

condi-tions occur Better still, this same component also enables the scheduling of

rou-tine maintenance tasks either on a one-time basis or on a recurring basis — for

example, once a month or, say, on the first Saturday of every month SQL Server

Agent is the service responsible for processing alerts and running scheduled jobs

SQL Server Agent service is not available in SQL Server Express Edition, for which scheduling of jobs has to be done using Windows Scheduler For more information on Windows Scheduler,

search the web, using your preferred search engine or consult Microsoft Windows

documentation.

Setting Up SQL Server Agent

Setting up SQL Server Agent is straightforward, as long as you avoid two pitfalls:

The first is rather elementary (a startup issue); the second (a security issue) is a

bit more subtle It makes sense to start with the easy one Because SQL Server

Agent is a Windows service, make sure that the service is restarted if anybody

reboots the server (Microsoft sets this service not to start by default when you