Re: timezone GUC

Robert Haas <robertmhaas@gmail.com> writes:
> If you have the timezone configured to a non-default value in
> postgresql.conf, and you comment it out and reload, it says:

> LOG:  parameter "TimeZone" removed from configuration file, reset to default

> ...but at least when I tested it, it didn't actually appear to reset
> it to the default.

Hm, interesting.  guc-file.l thinks this will fix it in such cases:
    /* Now we can re-apply the wired-in default */    set_config_option(gconf->name, NULL, context, PGC_S_DEFAULT,
               GUC_ACTION_SET, true);
 

but for variables where the powerup default is "do nothing just yet",
that, um, does nothing just yet.  The patch I just applied doesn't
change this behavior.  I suspect that this "re-apply" logic also fails
for cases where the intended default derives from environment variables.

Making this work as expected actually looks a bit nasty, because in the
case where the config file entry was there at system bootup, we never
did compute a state corresponding to its not being there.  So it's not
just a matter of rolling back to some prior state.
        regards, tom lane