Write various indexes used in Cognos?

There are many types of indexes used in Cognos. These are:

• Bitmap Indexes: A bitmap index is used to replace a list of rowids with the key values. Due to the presence of low cardinality and low updates, it is more efficient for data waring.
• B-tree indexes: B-tree indexes are used on the availability of high-cardinality, generally when we have too many distinct columns. It is mainly used for OLTP.
• Function-based indexes: These are created on the results of an expression or function.
• Reverse key and Composite Indexes: In the reverse key, the keys of an index are reversed and then stored.