Find Users logged into PostgreSQL

Question:Is there a query to run that will return all Users that are currently logged into PostgreSQL?

Answer: In PostgreSQL, there is a system view called pg_stat_activity which shows the current processes being run in the database. You can run a query against this system view that returns all of the Users that are currently have a process running in the PostgreSQL database.

To retrieve all Users logged into PostgreSQL, you can execute the following SQL statement:

SELECT DISTINCT usename

FROM pg_stat_activity;

This SELECT statement will return the users that are currently running a process in PostgreSQL.

TIP: You must have superuser privileges to see processes owned by other users. Otherwise, you will only see your own processes.

The pg_stat_activity view contains the following columns:

Column	Explanation
datid	Database ID where process is running
datname	Database name where process is running
pid	Process ID
usesysid	User ID (number assigned by PostgreSQL)
usename	User name (ie: postgres, fastread.aitechtonic, etc)
application_name	Application name
client_addr	Client's address
client_hostname	Client's hostname
client_port	Client's port number
backend_start
xact_start
query_start	Time when query was started
state_change	Time when the query's state was changed
waiting	Boolean value indicating query's waiting status (t or f)
state	State of query (ie: idle, active)
query	Current query