You tried to use pattern matching, but did not specify the leftmost character.

Specify the leftmost part of the key; *F* does not use the B-tree index, but F* does. If you cannot modify the search condition, the entire table must be scanned.

You tried to use just part of a multi-column key, but did not specify the leftmost column.

Specify the leftmost column of the multi-column key. If you cannot modify the search condition, create a secondary index with only the columns on which you are searching.

You are deleting frequently, as well as adding data.

To reclaim space, periodically select Shrink B-tree Index in the Modify Table Structure dialog, or use the MODIFY TO MERGE or MODIFY statements.