If nothing else is working, we may need to stop the server quickly, without caring about disconnecting the clients gently.
"Break the glass in case of emergency!"
The basic command to perform an emergency restart on the server is the following:
pg_ctl -D datadir stop -m immediate
We must use an immediate stop mode.
When you do an immediate stop, all users have their transactions aborted and all connections are disconnected. There is no clean shutdown, nor is there politeness of any kind.
An immediate mode stop is similar to a database crash. Some cached files will need to be rebuilt, and the database itself needs to undergo crash recovery when it comes back up.
Note that for DBAs with ...