"David G. Johnston" <david.g.johnston@xxxxxxxxx> writes: > On Monday, April 6, 2020, AC Gomez <antklc@xxxxxxxxx> wrote: >> If you issue an ALTER SERVER command and there are active connections >> with that server in use or new ones are coming in, what happens? Docs on >> this command say nothing regarding active processing using the server >> context and changes to it. So I assume it's just handled. > Not sure if there are exceptions but assume that nothing external will > change your current active session’s settings out from underneath you. Couple of comments here: * ALTER SERVER changes nothing until "pg_ctl reload" or similar is issued. The same goes for manually editing the config file (which is more or less the same thing, though on a different file). * Once you do issue a reload, individual sessions will adopt the new setting reasonably promptly, though not necessarily all at the same instant (assuming it's a setting that doesn't require a postmaster restart to take effect, in which case nothing happens). * A session that has a higher-priority source for the setting of a given GUC, such as a locally-issued SET, is not going to adopt the new setting from the config file. But it *will* adopt that setting on-the-fly if it has no other source of the setting. The priority rules are explained in the fine manual, IIRC. Possibly some clarification is needed? >> For example if you alter user/password, I assume that as long as prior >> user password is still good that actively running processes will keep going. > If you alter a password the old one is by definition no longer good...but > it doesn’t matter because authentication only happens once - during login. Right. Also, passwords are *not* managed through the GUC (server parameter) mechanism; what I just said about GUCs doesn't apply to them. regards, tom lane
