In what cases are indexes appropriate?

Indexes are appropriate when you need to speed up search, sorting, or data filtering operations in a database. They are especially useful for columns that are frequently used in queries with WHERE, JOIN, or ORDER BY conditions. Indexes allow the database to quickly find the needed records without scanning the entire table.

However, indexes are not always justified: they occupy additional space and slow down insert, update, and delete operations, as the index also needs to be updated. Therefore, indexes should be created for columns that are frequently involved in queries but rarely changed, and when the table is large enough for the speed gain to be noticeable.