What is the purpose of composite indexes in database design for Clarity?

• A. For typical query patterns involving multiple columns
• B. To slow down queries
• C. To store large binary data
• D. To enforce referential integrity

Answer: (A)

Composite indexes are indexes built from multiple columns, designed to accelerate queries that filter on more than one column. When you have common query patterns that specify several fields together, a composite index on those columns lets the database navigate the index in the same multi-column order, often quickly locating the matching rows without scanning the whole table. The order of the columns in the index matters, because queries using the leading column (and often the following ones) can use the index efficiently, and such indexes can even serve as a covering index if all needed data is contained in the index itself. This is why the purpose is to speed up typical multi-column query patterns. They don’t slow down queries, they aren’t meant for storing large binary data, and they aren’t used to enforce referential integrity—that’s handled by constraints like foreign keys.