In what cases can the use of indexes lead to a decrease in database performance?

Indexes can degrade database performance in the following cases:

• Frequent insert, update, and delete operations — indexes need to be updated when data changes, which slows down these operations.
• A large number of indexes on a single table — the overhead of maintaining all indexes increases.
• Indexes on columns with low selectivity (few unique values) — they are inefficient and can lead to additional costs.
• Using indexes in queries where they are not suitable — for example, full table scans might be faster for queries retrieving many rows.

Therefore, it is important to analyze the load and the nature of queries to balance the number and types of indexes.