Updating Statistics on an Index

Maintaining indexes statistics can improve the performance of many queries.

1. In the Administration Console view, select ASE Servers > Schema Objects > Tables > User Tables.
2. Click the Name field of the table, then click the drop-down arrow and select Properties.
3. In the left pane, click Indexes.
4. Click the Name field of the index, then click the drop-down arrow and select Update Statistics.
5. On the Command Type screen, select the update statistics command to run.
6. (Optional) On the Index Partitions screen, select the index partition to update.
7. (Optional) 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 more 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.
8. 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.
9. On the Sampling screen, specify whether to set sampling, and to what percentage.
10. On the Step Number screen, indicate whether to set the number of histogram steps, and how many.
11. On the Consumers screen, set the number of consumer processes to be used in parallel processing. The controls are enabled if the value for max parallel degree is 3 or greater.
12. 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.
13. On the Summary screen, verify your selections.
14. Click Finish.