Types of Indexes in Oracle Database

There are several types of indexes in Oracle database, each serving a specific purpose:

1. B-tree Index: This is the most common type of index in Oracle. It is best used for columns that are frequently queried with equality conditions, such as primary key columns.
2. Bitmap Index: Bitmap indexes are ideal for columns with low cardinality, meaning they have a small number of distinct values. They are efficient for queries that involve multiple OR conditions.
3. Function-based Index: This type of index is created based on the result of a function applied to a column. They are useful for queries that involve expressions or functions.
4. Reverse Key Index: Reverse key indexes help mitigate performance issues related to index contention in high-concurrency environments. They are beneficial for tables with monotonically increasing primary keys.
5. Clustered Index: Clustered indexes physically reorder the table data to match the order of the index. They are suitable for range queries and improve the performance of queries that access sequential data.

Choosing the appropriate index type depends on the specific use case and query patterns. It is essential to consider factors such as data distribution, query performance requirements, and the expected workload on the database.