User vs Role in PostgreSQL: Key Differences and When to Use Each

In PostgreSQL, a user is a legacy term for a role with login privileges, while a role is a more general concept that can represent a user or a group. Roles can own database objects and have permissions, and users are simply roles that can log in.

Quick Comparison

Here is a quick comparison between user and role in PostgreSQL to understand their main differences.

Aspect	User	Role
Definition	Legacy term for a role with login ability	General entity for permissions and ownership
Login Capability	Always has login privilege	May or may not have login privilege
Grouping	Cannot be a group	Can represent a group of users or roles
Permission Assignment	Can own objects and have permissions	Can own objects and have permissions
Creation Command	CREATE USER (alias for CREATE ROLE with login)	CREATE ROLE
Modern Usage	Deprecated in favor of roles	Preferred for all access control

Key Differences

PostgreSQL treats user as a special kind of role that has the ability to log in. Originally, user was a separate concept, but since PostgreSQL 8.1, user is just an alias for a role with login rights.

A role can represent either a single user or a group of users. Roles without login privileges are often used as groups to simplify permission management. This means you can assign permissions to a role and then grant that role to multiple users.

While user implies login capability, role is more flexible and is the recommended way to manage database access. Using roles allows better organization and control over permissions and ownership of database objects.

User Example

This example shows how to create a user in PostgreSQL, which is actually creating a role with login permission.

sql

CREATE USER alice WITH PASSWORD 'securepass';

-- Check if user exists
SELECT rolname, rolcanlogin FROM pg_roles WHERE rolname = 'alice';

Output

 rolname | rolcanlogin 
---------+-------------
 alice   | t
(1 row)

Role Equivalent

This example creates a role with login capability, which is equivalent to creating a user.

sql

CREATE ROLE bob WITH LOGIN PASSWORD 'strongpass';

-- Check if role exists
SELECT rolname, rolcanlogin FROM pg_roles WHERE rolname = 'bob';

Output

 rolname | rolcanlogin 
---------+-------------
 bob     | t
(1 row)

When to Use Which

Choose role for all new PostgreSQL projects because it is the modern, flexible way to manage permissions and groups. Use roles without login to create groups and assign permissions collectively.

Use user only if you are working with legacy scripts or tools that expect the user keyword, but know it is just an alias for a role with login.

In short, prefer role for clarity and better permission management, and treat user as a legacy synonym.

Key Takeaways

In PostgreSQL, a user is just a role with login privileges.

Roles are more flexible and can represent users or groups.

Use roles to manage permissions and group users effectively.

CREATE USER is an alias for CREATE ROLE with login.

Prefer roles for new projects and legacy users only when needed.