Query below returns list of users in current database.

Query

select usesysid as user_id,
       usename as username,
       usecreatedb as db_create,
       usesuper as is_superuser,
       valuntil as password_expiration
from pg_user
order by user_id

Columns

• user_id - id of the user
• username - user name
• db_create - flag indicating if user can create new databases
• is_superuser - flag if user have superuser privileges
• password_expiration - date of user password expiration

Rows

• One row represents one user in the database
• Scope of rows: all users in the database
• Ordered by user id

Sample results

Those results show that there are 4 users in current database.