May 2018
Intermediate to advanced
576 pages
30h 25m
English
To reload the configuration files, we send the SIGHUP signal to the postmaster, which then passes that to all connected backends. That's why some people call reloading the server sigh-up-ing.
If you look at the pg_settings catalog table, you'll see that there is a column named context. Each setting has a time and a place where it can be changed. Some parameters can only be reset by a server reload, and so the value of context for those parameters will be a sighup. Here are a few of the parameters you'd want to change sometimes during server operation (there are others, however):
postgres=# SELECT name, setting, unit ,(source = 'default') as is_default FROM pg_settings WHERE context = 'sighup' AND (name like '%delay' or name ...