list of users in postgres

Guri Bee

2 min read

·

19-10-2024

1

0

Share

A Comprehensive Guide to Listing PostgreSQL Users

Knowing who has access to your PostgreSQL database is crucial for security and administration. This article explores various methods for listing PostgreSQL users, offering insights and practical examples for efficient user management.

Why is it Important to List PostgreSQL Users?

Understanding the users associated with your PostgreSQL database is paramount for multiple reasons:

• Security: Identifying unauthorized users can help prevent malicious activities or data breaches.
• Resource Management: Knowing the number and roles of users can optimize resource allocation and prevent performance issues.
• Accountability: Tracking user activity and changes helps maintain transparency and identify potential security vulnerabilities.

Methods to List PostgreSQL Users

Here are some methods for retrieving a list of PostgreSQL users, sourced from GitHub discussions and refined for clarity:

1. Using the \du command:

This command is a quick and straightforward way to list users directly within the PostgreSQL shell (psql).

\du

Example output:

                                    List of roles
  Role name  |  Attributes  |  Member of  |  Inherit  |  Superuser  |  Create role  |  Create DB  |  Can login  |  Replication  |  Connection limit  |  Password  |  Valid until  |
------------+---------------+-------------+-----------+--------------+----------------+-------------+-------------+---------------+-------------------+------------+----------------+
 postgres   |  createdb     |             | t         | t            | t              | t           | t            | f              | -1                |            |                |
  user1     |  createdb     |             | t         | f            | f              | f           | t            | f              | -1                |            |                |
  user2     |              |             | t         | f            | f              | f           | t            | f              | -1                |            |                |
(3 rows)

2. Utilizing the pg_user system table:

This system table provides detailed information about each user, including their roles and privileges.

SELECT usename, rolname
FROM pg_user
JOIN pg_authid ON pg_user.usesysid = pg_authid.oid;

Example output:

 usename | rolname
---------+---------
 postgres | postgres
 user1   | user1
 user2   | user2
(3 rows)

3. The SELECT * FROM pg_roles query:

This query retrieves all information about PostgreSQL roles, including user accounts, system roles, and groups.

SELECT * FROM pg_roles;

Example output:

 oid  | rolname   |  rolsuper  | rolcreaterole | rolcreatedb |  rolcanlogin  |  rolreplication  | rolconnlimit  |  rolinherit | rolbypassrls | rolvaliduntil |
------+-----------+------------+--------------+-------------+---------------+-----------------+---------------+-------------+---------------+----------------+
 16384| postgres   | t          | t            | t           | t             | f               | -1            | t           | f              |                |
 16387| user1     | f          | f            | f           | t             | f               | -1            | t           | f              |                |
 16388| user2     | f          | f            | f           | t             | f               | -1            | t           | f              |                |
(3 rows)

Further Exploration

• User Creation: You can create new PostgreSQL users with the CREATE ROLE command. This allows you to control their permissions and access levels.
• User Modification: The ALTER ROLE command enables you to update user properties, such as their password or permissions.
• User Deletion: The DROP ROLE command permanently removes users from your database.

Conclusion

Listing PostgreSQL users is essential for maintaining database security and optimizing resource allocation. By understanding the various methods provided in this article, you can effectively manage user accounts and ensure the integrity of your PostgreSQL system. Remember to consult the official PostgreSQL documentation for more advanced user management techniques and security practices.