Here are some additional suggestions that can lead to improved performance when you are creating and using indexes:
Modify the logical design to make use of an artificial column and a lookup table for tables that require a large index entry.
Reduce the size of an index entry for a frequently used index.
Drop indexes during periods when frequent updates occur and rebuild them before periods when frequent selects occur.
If you do frequent index maintenance, configure your server to speed up the sorting.
See “Configuring Adaptive Server to speed sorting” for information about configuration parameters that enable faster sorting.