There are two enhancements to create index:
The create index command allows the user to specify ascending or descending order for each column in the index. In earlier versions, all indexes were created in ascending order for all columns. Scans that needed to read the data in reverse order could scan the index backward, but if the required order was a mix of ascending and descending order on the keys, the query needed to perform a sort step. Performance can be improved by matching the index ordering to the ordering used by most queries.
Indexes can include as many as 31 key columns, an increase from 16 in previous versions. The maximum total number of bytes allowed for index keys is 600.
