Can you list the types of indexes used in SQL and their features?

In SQL, there are several main types of indexes, each optimized for specific tasks:

• B-Tree index — the most common type. Suitable for fast searches, sorting, and range queries. Used by default in many DBMS.

• Hash index — efficient for exact key lookups but does not support range queries or sorting.

• Bitmap index — well-suited for columns with low cardinality (e.g., gender, status). Used in analytical databases.

• Full-text index — designed for full-text search on text fields.

• Spatial index — used for geographic data and spatial queries.

Example of creating a B-Tree index in PostgreSQL:

CREATE INDEX idx_users_name ON users(name);

The choice of index type depends on the nature of the queries and data structure.