SQL Server 2008 R2 : The Maintenance Plan Wizard (part 2)

- Free product key for windows 10
- Free Product Key for Microsoft office 365
- Malwarebytes Premium 3.7.1 Serial Keys (LifeTime) 2019

Maintaining Indexes and Statistics

Maintaining indexes and statistics is essential in most database environments, including those that have frequent changes to the data. These changes can cause tables and their indexes to become fragmented and inefficient. These types of environments can also lead to outdated statistics on indexes. Outdated statistics can cause the query engine to make less-than-optimal choices when determining the best access path to the data.

The maintenance of indexes and statistics is facilitated through the use of three different tasks in the Maintenance Plan Wizard: Reorganize Index, Rebuild Index, and Update Statistics. Using the Reorganize Index task is equivalent to running the ALTER INDEX REORGANIZE command. This task defragments and compacts clustered and nonclustered indexes on tables and views. This helps improve index-scanning performance and should improve overall response time. The operation is always done online and is also equivalent to running the DBCC INDEXDEFRAG command.

Figure 7 shows the screen you use to define the Reorganize Index task. This screen allows you select tables, views, or tables and views. You can also select specific tables or views that you want to reorganize. The Compact Large Objects option is equivalent to ALTER INDEX LOB_COMPACTION = ON. It causes data in large object (LOB) data types, such as image or text objects, to be compacted.

Figure 7. The Reorganize Index task options in the Maintenance Plan Wizard.

The Reorganize Index task moves the leaf-level pages so that they match the logical ordering of the index. This behavior improves performance, but it is not as extensive as the Rebuild Index task, which is equivalent to the ALTER INDEX REBUILD command. It is also equivalent to the DBCC DBREINDEX command. When the Rebuild Index task is executed, it rebuilds the indexes from scratch. This rebuilding can achieve the best performance results, but it also has the most impact on users of the database.

Figure 8 shows the options available for rebuilding an index with the Maintenance Plan Wizard.

Figure 8. The Rebuild Index task options in the Maintenance Plan Wizard.

The options for rebuilding are separated into two sections: Free Space Options and Advanced Options. The Free Space Options section pertains to the amount of free space left in the index pages after the rebuild operation completes. This free space is defined by the fill factor for the index. When the Reorganize Pages with the Default Amount of Free Space option is used, the fill factor is reset to the value used when the index was created. The other option, Change Free Space per Page Percentage To, allows you to choose a new fill factor value to be used for all indexes that have been selected for the rebuild operation.

The following advanced Rebuild Index task options are available:

  • Sort Results in tempdb— This option is equivalent to the SORT_IN_TEMPDB option for the index. It causes tempdb to be used to store intermediate results while rebuilding the index. If this option is not used, these intermediate results are stored in the database in which the index resides. Storing the results in tempdb can help prevent unnecessary growth of the user database in which the index is being rebuilt.

  • Keep Index Online While Reindexing— This option is equivalent to the ONLINE option for the index. It allows users to access the underlying table and associated indexes during the index rebuild operation. If this option is not used, the index rebuild is on offline operation, and a table lock is held on the table that is having its indexes rebuilt.

The maintenance of statistics can be just as important as the maintenance of indexes on a table. Statistics contain information about the distribution of data in tables and indexes and provide valuable information to the SQL Server query engine. When the statistics are outdated, the query engine may not make the best decisions for getting the data.

Fortunately, there are database options that cause statistics to be automatically updated. The AUTO UPDATE STATISTICS and AUTO UPDATE STATISTICS ASYNCHRONOUSLY options cause index statistics to be created automatically. However, in some situations the automatic update of statistics does not happen often enough, or the update happens at inopportune times and can cause performance issues. You can address these situations by scheduling the updating of statistics via a maintenance plan, using the Update Statistics task.

Figure 9 shows the Maintenance Plan Wizard screen for setting the Update Statistics task options.

Figure 9. The Update Statistics task options in the Maintenance Plan Wizard.

The top portion of the Define Update Statistics Task screen is much like the option screens for maintaining indexes. You can choose the type of objects (tables or views) on which you want to update statistics, or you can focus on specific tables or views. The Update options at the bottom of the screen identify the types of statistics to be updated. If the All Existing Statistics option is selected, statistics for both indexes and columns are updated. Statistics on columns exist if the AUTO CREATE STATISTICS option has been set to ON or the statistics were manually created. The other two update options on the screen allow you to focus the update of statistics on columns only or indexes only.

Scheduling a Maintenance Plan

One of the greatest features of a maintenance plan is that you can schedule it. Scheduling takes manual work off your plate and provides consistency that might be missed if the plan had to be run manually. History is kept for each of the scheduled executions, which provides an audit trail, and notifications can be tied to the scheduled plans to allow a user to respond to failures or other results from the plan.

A schedule can be created for an entire maintenance plan or individual schedules can be created for each task in the plan. The scheduling selection is available on the Select Plan Properties screen, which is one of the first screens displayed while using the Maintenance Plan Wizard (refer to Figure 1). Choose the Separate Schedules for Each Task option to create a schedule for each task. The default option is Single Schedule for the Entire Plan or No Schedule. If you choose the option for separate schedules, the Schedule Change button is enabled on the task definition screen and this schedule is tied to that specific task.

Both scheduling options utilize the same scheduling screen. The screen to set scheduling options, the Job Schedule Properties dialog box shown in Figure 10, appears when you click on the Schedule Change button. This screen contains the same flexible scheduling features available in the SQL Server Agent.

Figure 10. Scheduling options in the Maintenance Plan Wizard.

When a maintenance plan is saved, a scheduled job with the same name as the maintenance plan is created. The job schedule defined for the maintenance plan is applied to the scheduled job, and the SQL Server Agent manages the execution of the job, based on the schedule. Scheduling changes made to the maintenance plan are automatically reflected in the scheduled job. In addition, if the name of the maintenance plan is changed, the name of the scheduled job is changed as well. If an attempt is made to delete the scheduled job related to the maintenance plan, an error is returned, disallowing the deletion.


Scheduling in the Maintenance Plan Wizard is limited to one schedule per plan or task depending on which option you choose. You can surpass this limitation by adding additional schedules to the scheduled job associated with the maintenance plan. To do so, you simply open the associated scheduled job located in the SQL Server Agent node in SSMS and create the additional schedules. This capability is handy when you want a varied execution, such as a weekly schedule combined with daily executions of the same plan.

The scheduled job associated with a maintenance plan executes an SSIS package. Figure 11 shows an example of the scheduled job step for a SQL Server 2008 maintenance plan.

Figure 11. Scheduling jobs for a maintenance plan.

The utilization of SSIS in the execution of maintenance plans was a significant change in SQL Server 2005. SSIS provides added workflow capabilities and extends the feature set for maintenance plans. The scheduled job step that executes an SSIS package for the maintenance plan shows some of the options and flexibility of SSIS, but the real power is in the maintenance plan editor and the Business Intelligence Design Studio (BIDS) used to manage all SSIS packages. 

An integral part of a scheduled maintenance plan is the notification and reporting capabilities. The Select Report Options screen is displayed at the end of the Maintenance Plan Wizard (see Figure 12).

Figure 12. Reporting options in the Maintenance Plan Wizard.

The option Write a Report to a Text File provides details about the execution of each maintenance plan. This option should be selected for most plans, and it provides excellent information for researching past executions and diagnosing any maintenance plan failures.

The E-mail Report option provides a means for notifying a SQL Server operator when a task fails. You must have Database Mail enabled to be able to use this option, and the operator selected must have a valid email address to receive the notification. You can also edit the job associated with the maintenance plan after it has been created and set up notification there. The notification options on the scheduled job are more extensive than those in the Maintenance Plan Wizard.


If you have a maintenance plan generate a report, you need to make sure you have a means for cleaning up the files. The wizard does not create a plan that deletes the older report files. You can address this situation by modifying the plan after the wizard has created it and adding a Maintenance Cleanup task. This same task can be used to delete old database backup files. The modification of a maintenance plan and addition of the Maintenance Cleanup task are discussed in the following section.

Top 10
Free Mobile And Desktop Apps For Accessing Restricted Websites
TOYOTA CAMRY 2; 2.5 : Camry now more comely
KIA SORENTO 2.2CRDi : Fuel-sipping slugger
How To Setup, Password Protect & Encrypt Wireless Internet Connection
Emulate And Run iPad Apps On Windows, Mac OS X & Linux With iPadian
Backup & Restore Game Progress From Any Game With SaveGameProgress
Generate A Facebook Timeline Cover Using A Free App
New App for Women ‘Remix’ Offers Fashion Advice & Style Tips
SG50 Ferrari F12berlinetta : Prancing Horse for Lion City's 50th
- Messages forwarded by Outlook rule go nowhere
- Create and Deploy Windows 7 Image
- How do I check to see if my exchange 2003 is an open relay? (not using a open relay tester tool online, but on the console)
- Creating and using an unencrypted cookie in ASP.NET
- Directories
- Poor Performance on Sharepoint 2010 Server
- SBS 2008 ~ The e-mail alias already exists...
- Public to Private IP - DNS Changes
- Send Email from Winform application
- How to create a .mdb file from ms sql server database.......
programming4us programming4us