Is a Primary Key an index in a database?

Yes, in most relational databases, the Primary Key automatically creates a unique index. This ensures fast search and guarantees the uniqueness of values in the column or set of columns defining the primary key.

The index helps the database efficiently find records by the primary key, which speeds up selection, update, and delete operations.

Thus, the Primary Key is not just a uniqueness constraint but also an index that maintains data integrity and query performance.