Unique and Primary Key Indexes
Understand how PostgreSQL automatically backs primary keys and unique constraints with indexes, and how to use unique indexes to enforce data integrity efficiently.
Constraints Need Indexes
To enforce uniqueness, PostgreSQL must check existing rows fast — so it auto-builds a unique index behind every unique constraint and primary key.
Primary Key Index
Declaring a primary key creates a unique B-tree index on those columns and marks them NOT NULL. The code shows it in action.
CREATE TABLE users (
id SERIAL PRIMARY KEY,
email TEXT
);All lessons in this course
- Why Indexes Matter
- B-Tree Index Basics
- Creating and Dropping Indexes
- Unique and Primary Key Indexes