PSQL: List Connections To A Database

The pg_stat_activity table can be used to determine what connections there currently are to the PostgreSQL server and to a particular database. To see the process ids and usernames of all connection to your PostgreSQL server, run the following query:

> select pid, usename from pg_stat_activity;
  pid  |  usename
-------+------------
 57174 | jbranchaud
 83420 | jbranchaud

Include datname in the requested columns to figure out the database of each connection.

> select pid, usename, datname from pg_stat_activity;
  pid  |  usename   |  datname
-------+------------+-----------
 57174 | jbranchaud | hr_hotels
 83420 | jbranchaud | pgbyex

The results can be restricted to a particular database as necessary.

> select pid, usename from pg_stat_activity where datname = 'hr_hotels';
  pid  |  usename
-------+------------
 57174 | jbranchaud

Via jbranchaud/til.