The Rebuild Indexes option on the Tables and Indexes view allows you to select tables to rebuild. Rebuilding your tables allows you to decrease the amount of fragmentation on a table. High table fragmentation can lead to overall performance bottlenecks on your SQL Server instance.
When you click Rebuild Indexes from the SQL Diagnostic Manager Console, the Select Tables window opens and allows you to choose the table indexes to rebuild.
If you are rebuilding indexes on a very large table the rebuild process could take several minutes to complete. While the rebuild is in process, the table is locked and users are unable to access it.
Once the indexes are rebuilt, the % Fragmentation (Current) column displays showing you the results.
If you are rebuilding a very large index, the SQL Diagnostic Manager Console checks for the rebuild status for 90 seconds. If the rebuild is not complete after 90 seconds, the % Fragmentation (Current) column does not display the new value until the next table statistics collection occurs.