Doing an index what-if analysis

You can do an index what-if analysis for a single query or a workload tuning task.

To do an index what-if analysis and generate recommendations:

1. Create a tuning task on a single query or workload, with Recommend new indexes tuning option selected.
2. When the tuning task is completed, go to Tuning > Tuning results page to view the result list.
3. In the Tuning results page, select the tasks with the Result displaying as Success and click View result.
   The Advisor recommendations page displays.
4. Click Indexes from the Advisors menu.
   The Storage comparison chart, Performance comparison chart, and Index Recommendations table are displayed.
5. From the Index Recommendations action bar, click Run what-if analysis.
   The Configuration page displays.
6. In the Configuration page, you can customize to remove recommended indexes, virtually drop existing indexes, and add new indexes.
7. Click Run what-if analysis to launch the what-if analysis tuning task.
8. When the tuning task is completed, go to Tuning > Tuning results page to view the result list.
9. From the Tuning results page, click the name of the tuning task to view the what-if analysis result.
   The Storage comparison and Performance comparison charts are displayed on the left side. These charts provide a comparison between the original cost and the after-change cost if the customized recommendation DDLs are applied. The Suggested change recommendation DDLs are displayed on the right side.

   Note: If you are doing an index what-if analysis for a single query, the what-if analysis results page displays the Access plan graph tab to view the revised access plan graph with the virtual indexes.