Best Practice in Rebuilding Index in SQL Server

For every Database admin, ensuring the smooth performance of the SQL Server is a headache. They need to perform various tasks and tricks for a productive and fast SQL database. One such common task is to keep the Index fragmentation in check. While this is a challenge for the DBAs, Index Fragmentation can be controlled by reorganizing and rebuilding.

Rebuilding Index in SQL Server is the method often used when the fragmentation level goes higher. If you want to improve the performance of SQL database, you have to rebuild the index. But the question is when and how to perform this task. This write-up will focus on the best practices in rebuilding index of SQL Server. We will also discuss when is the right time to conduct this task easily.

Rebuilding Index in SQL Database – Know Why and When to Perform?

It is known to the SQL Server users that database performance gets significantly hampered if the SQL database becomes full of fragmented indexes. As Index Fragmentation keeps increasing along with the database usage, admins should be careful about the fragmentation rate. Depending on the database size, DBAs should fix a schedule when the index fragmentation will be checked using “sys.dm_db_index_physical_stats” command. When this command is run, users can learn about the percentage of index fragmentation in SQL database.

If the percentage is as low as 10%, no additional action is needed. If the level is between 10%- 30%, you have to rebuild the index to enhance its performance. Only when it crosses the 30% bar, the question of rebuilding index in SQL Server comes to the scene. However, some SQL Server experts recommend performing Index rebuilding only when the fragmentation rate reaches 80% or 90%. Since rebuilding index is a resource-consuming task, database admins should consider how much the fragmentation affects the database performance before rebuilding the index.

Best Practices in Rebuilding Index in SQL Server

If you are interested in rebuilding indexes, it is better to follow certain basic rules, known as the best practices in Index rebuilding. For example, if you are using any SQL Server edition other than the Enterprise Edition, then this task should be done offline. Since the feature of Online Index Rebuilding got introduced in SQL Server 2005 Enterprise Edition, any earlier version users need to perform it offline. With Online index rebuilding, the index never goes offline and table also remains available for use during the process.

In case of SQL Enterprise Editions that support online index rebuild, the online process takes more time than offline rebuilding. That is why, offline index rebuilding is highly recommended if the company can afford downtime. To minimize the downtime, it should be done when minimum people are using the database or it should be done along with scheduled maintenance tasks. Therefore, nighttime is perfect to schedule index rebuilding. It is also suggested to conduct this task at least once a week. If you do not have any maintenance window for your database, you can try doing Online rebuilding.

Rebuilding Index in SQL Server consumes a lot of resources. So performing it too regularly will create inconvenience to the database with scarce resources. Database admins should consider their database capacity and resources before scheduling the index rebuilding.

Note:  Get to know How to Deal with Index Corruption in SQL Server

Concluding Thoughts

Index fragmentation is a common situation in all SQL databases. The productivity of the SQL Server depends on the level of Index fragmentation. Only a controlled Index fragmentation rate is desirable for smooth functioning of SQL Server. Among many approaches that keep the fragmentation level in control, rebuilding Index is a popular one.
In this process, logical index fragmentation is removed, statistics get updated and database page space is emptied. Therefore, users should include this in their maintenance scheduling window. They can also learn about the best practices in rebuilding index in SQL Server from this post. Also, consider the situation of your own SQL database to customize the rebuilding process.

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