What is a composite index and when would you use it?

A composite index is an index that is created on multiple columns. It is used when a query

filters or sorts based on more than one column. Composite indexes are especially useful

when queries frequently involve conditions on multiple columns.

• Example Use Case: If a query filters by both last_name and first_name,

creating a composite index on (last_name, first_name) will speed up the

query.

Example of creating a composite index:

CREATE INDEX idx_lastname_firstname ON employees(last_name,

first_name);