PostgreSQL Tutorial: CURRENT_USER Function

Summary: in this tutorial, you will learn how to use the PostgreSQL CURRENT_USER function to return the name of the currently logged-in database user.

Table of Contents

Introduction to the PostgreSQL CURRENT_USER function

The PostgreSQL CURRENT_USER is a function that returns the name of the currently logged-in database user.

Here’s the syntax of the CURRENT_USER function:

CURRENT_USER

The function returns the name of the current effective user within the session.

In other words, if you use the SET ROLE statement to change the role of the current user to the new one, the CURRENT_USER will reflect the new role.

In PostgreSQL, a role with the LOGIN attribute represents a user. Therefore, we use the terms role and user interchangeably.

To get the original user who connected to the session, you use the SESSION_USER function.

PostgreSQL CURRENT_USER function example

First, open the command prompt on Windows or a terminal on Unix-like systems and connect to the PostgreSQL server using psql:

psql -U postgres

Second, use the CURRENT_USER function to get the currently logged-in user:

SELECT CURRENT_USER;

Output:

 current_user
--------------
 postgres
(1 row)

Third, create a new role called bob:

CREATE ROLE bob WITH LOGIN PASSWORD 'SecurePass1';

Fourth, change the role of the current user to bob:

SET ROLE bob;

Fifth, execute the CURRENT_USER function:

SELECT CURRENT_USER;

It returns bob instead:

 current_user
--------------
 bob
(1 row)

Six, use the SESSION_USER function to retrieve the original user who connected to the session:

SELECT SESSION_USER;

Output:

 session_user
--------------
 postgres
(1 row)

The SESSION_USER function returns postgres, not bob.

Summary

• Use the CURRENT_USER function to return the current effective user within the session.
• Use the SESSION_USER function to return the original user who connected to the session.