Unnamed Constraints

Check name: UnnamedConstraintCheck

Lock type: None (best practice warning)

Bad

Adding constraints without explicit names results in auto-generated names from Postgres. These names vary between databases and make future migrations difficult — you can’t reliably reference a constraint you don’t know the name of.

-- Unnamed UNIQUE constraint
ALTER TABLE users ADD UNIQUE (email);

-- Unnamed FOREIGN KEY constraint
ALTER TABLE posts ADD FOREIGN KEY (user_id) REFERENCES users(id);

-- Unnamed CHECK constraint
ALTER TABLE users ADD CHECK (age >= 0);

Good

Always name constraints explicitly using the CONSTRAINT keyword:

-- Named UNIQUE constraint
ALTER TABLE users ADD CONSTRAINT users_email_key UNIQUE (email);

-- Named FOREIGN KEY constraint
ALTER TABLE posts ADD CONSTRAINT posts_user_id_fkey FOREIGN KEY (user_id) REFERENCES users(id);

-- Named CHECK constraint
ALTER TABLE users ADD CONSTRAINT users_age_check CHECK (age >= 0);

Naming Conventions

• UNIQUE: {table}_{column}_key or {table}_{column1}_{column2}_key
• FOREIGN KEY: {table}_{column}_fkey
• CHECK: {table}_{column}_check or {table}_{description}_check

Named constraints make future migrations predictable:

-- Easy to reference in later migrations
ALTER TABLE users DROP CONSTRAINT users_email_key;