Sometimes I want to alter a PostgreSQL database in some way but I am prevented by other connections, as this error indicates:
ERROR: database "my_database" is being accessed by other users DETAIL: There are 2 other session(s) using the database.
It's not always easy to figure out which applications have open sessions, so here's a great script I found on Stack Overflow to terminate all connections to the database:
SELECT pg_terminate_backend(procpid) FROM pg_stat_activity WHERE -- don't kill my own connection! procpid <> pg_backend_pid() -- don't kill the connections to other databases AND datname = 'my_database' ;