different types of database indexes.

Different types of database indexes include:

1. **B-Tree Index:** A balanced tree structure that maintains sorted data, allowing for efficient insertion, deletion, and lookup operations. Commonly used for primary and secondary indexes.

2. **Hash Index:** Uses a hash function to map search keys to corresponding values, offering fast lookup for exact match queries.

3. **Bitmap Index:** Uses bitmaps for each distinct value, making it efficient for read-heavy databases and queries with many AND, OR, and NOT operations.

4. **Clustered Index:** Determines the physical order of data in the table, meaning the table is stored in the same order as the index. A table can have only one clustered index.

5. **Non-Clustered Index:** Stores a separate structure with pointers to the data rows, allowing multiple non-clustered indexes per table for faster searches.

6. **Full-Text Index:** Optimizes the performance of full-text search queries, allowing efficient searching of text columns for keywords and phrases.

7. **Spatial Index:** Used for geospatial data to optimize queries involving spatial relationships and geometries, such as locations and shapes.

Each type of index is designed to optimize specific types of queries and operations within a database.