There are many ways to change the database's parameters beyond just editing its configuration file and restarting. Understanding these can be critical to reducing server downtime just for routine configuration changes, as well as making sure you're adjusting the parameter you want at the time when you want the change to take effect.
Interacting with the live configuration
Defaults and reset values
The database has two things that you might refer to as a default, depending on your context. The first type of default is what the server will set the value to if you don't ever change it to the setting the server starts with before it has even read the postgresql.conf file. Starting in PostgreSQL 8.4, you can check...
