Updating Statistics on an Index

Maintaining statistics on indexes can improve the performance of many queries.

1. In the Administration Console view, select ASE Servers > Schema Objects > Tables > User Tables > ..
2. Select the table that contains the index on which to run update statistics.
3. Click Properties.
   You see the Table Properties screen.
4. Select the Index screen.
5. Select the index on which to run update statistics.
6. Select Update Statistics to start the Update Statistics wizard.
7. On the Command Type screen, select the update statistics command to run.
8. On the Index Partitions screen, select the index partition to update.
9. On the Hashing screen, select:
   • The type of hashing:
     • Partial hashing – for columns that have 65536 or fewer unique values.
     • With hashing – for columns that have greater than 65536 unique values.
     • No hashing.
   • A value for max resource granularity (which indicates the maximum percentage of the system’s resources a query can use), if applicable.
10. Click Next.
11. On the Histogram Tuning screen, set the histogram tuning factor. The size of the histogram is established by multiplying the number of steps with the value for histogram tuning factor.
12. Click Next.
13. On the Sampling screen, specify whether to set sampling, and to what percentage.
14. Click Next.
15. On the Step Number screen, indicate if want to set the number of histogram steps, and how many.
16. Click Next.
17. On the Consumers screen, set the number of consumer processes to be used in parallel processing, and the number. The controls are enabled if the value for max parallel degree is 3 or greater.
18. Click Next.
19. On the DataChange Threshold screen, indicate whether to run update statistics when it reaches a data change threshold, and if so, the value of the threshold.
20. Click Next.
21. On the Summary screen, verify your selections.
22. Click Finish.