PostgreSQL automatically creates a B-tree when you add a primary key or unique constraint. True or False?

PostgreSQL automatically creates a B-tree when you add a primary key or unique constraint. True or False?

• A. True
• B. False
• C. Only when unique constraints
• D. Only when there are no text columns

Answer: (A)

PostgreSQL enforces primary keys and unique constraints by creating an index on the constrained columns. The index method used for these constraints is B-tree by default because it handles exact matches and ordered ranges efficiently, which is exactly what’s needed to ensure uniqueness and support fast lookups. So when you add a primary key or a unique constraint, PostgreSQL automatically creates a B-tree index. The other statements aren’t accurate: both kinds of constraints use a B-tree by default, text columns are fine with B-tree, and it’s not limited to only unique constraints.

PostgreSQL enforces primary keys and unique constraints by creating an index on the constrained columns. The index method used for these constraints is B-tree by default because it handles exact matches and ordered ranges efficiently, which is exactly what’s needed to ensure uniqueness and support fast lookups. So when you add a primary key or a unique constraint, PostgreSQL automatically creates a B-tree index. The other statements aren’t accurate: both kinds of constraints use a B-tree by default, text columns are fine with B-tree, and it’s not limited to only unique constraints.