PostgreSQL: How to Restrict User Access

PostgreSQL allows fine-grained access control using roles and privileges.

Revoke All Access

REVOKE ALL ON DATABASE mydb FROM username;

Grant Read-Only Access

GRANT CONNECT ON DATABASE mydb TO username;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO username;

Prevent Future Table Access

ALTER DEFAULT PRIVILEGES
REVOKE ALL ON TABLES FROM username;

This ensures the user can only read data and not modify it.