Some of the database server parameters require you to stop and start the server again fully. Doing this as quickly as possible can be very important in some cases. The best time to do this is usually a quiet time, with lots of planning, testing, and forethought. Sometimes, not everything goes according to plan.
The basic command to restart the server is the following:
pg_ctl -D datadir restart -m fast
A restart is just a stop followed by a start, so it sounds very simple. In many cases, it will be simple, but there are times when you'll need to restart the server while it is fairly busy. That's when we need to start pulling some tricks to make that restart happen faster.
First, the stop performed needs to be a fast stop. If we do a default or "smart" stop, then the server will just wait for everyone to finish. If we do an immediate stop, then the server will crash, and we will need to crash-recover the data, which will be slower overall.
The running...