In which situations is it preferable to use different types of indexes in a database?

Different types of indexes in a database are used depending on the nature of the data and queries:

• B-Tree index — the most common, suitable for fast exact match and range searches (e.g., WHERE age BETWEEN 20 AND 30).
• Hash index — efficient for exact key lookups but does not support range queries.
• Bitmap index — useful for columns with low cardinality (e.g., gender, status), especially in analytical systems.
• Full-text index — used for searching within text, when you need to find words or phrases inside large text fields.

The choice of index depends on:

• Data type and distribution
• Frequency and type of queries (exact match, range, full-text search)
• Data volume and update frequency (indexes slow down insert/update)

For example, a field with unique identifiers is better suited for a B-Tree index, while for searching descriptions, a full-text index is preferable.