When you perform any data modification operations (INSERT, UPDATE, or DELETE statements) table fragmentation can occur. When changes are made to the data that affect the index, index fragmentation can occur and the information in the index can get scattered in the database. Fragmented data can cause SQL Server to perform unnecessary data reads, so a queries performance against a heavy fragmented table can be very poor.
Rebuilding an index is a more efficient way to reduce fragmentation in comparison with dropping and re-creating an index, this is because rebuilding an index is done by one statement.
The DBCC DBREINDEX statement cannot automatically rebuild all of the indexes on all the tables in a database it can only work on one table at a time. You can write your own script to rebuild all the indexes on all the tables in a database
TableName - Is the name of the table in your DataBase.
Index_name - Is the name of the index to rebuild. (refer to image below)
Fillfactor - Is the percentage of space on each index page to be used for storing data when the index is created or rebuilt. Default is 100.
DBCC DBREINDEX ('TableName','Index_Name',fillfactor)
DBCC DBREINDEX ('Categories')
DBCC DBREINDEX ('Categories','Categoryname',80)
- It Can improve your database perfomance.