Types of Indexes in Oracle Database

There are several types of indexes that can be used in Oracle Database to improve queries performance:

1. B-tree Index: This is the most common type of index in Oracle, which stores keys in a sorted tree structure for efficient searching.
2. Bitmap Index: Bitmap indexes are useful for columns with low cardinality, where there are only a few distinct values.
3. Function-based Index: These indexes are based on function evaluations, allowing for indexed access to data based on function results.
4. Global Index: A global index is one that includes data from all partitions of a partitioned table.
5. Local Index: A local index is specific to a particular partition of a partitioned table.
6. Reverse Key Index: This type of index reverses the bytes of each key before inserting it, to reduce contention on right-hand index leaf blocks.

It is important to carefully consider the type of index to use based on the specific requirements of the application and the data being indexed.