timezone GUC

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.

assign_timezone() has this to say:

/*
* UNKNOWN is the value shown as the "default" for TimeZone in
* guc.c. We interpret it as being a complete no-op; we don't
* change the timezone setting. Note that if there is a known
* timezone setting, we will return that name rather than UNKNOWN
* as the canonical spelling.
*
* During GUC initialization, since the timezone library isn't set
* up yet, pg_get_timezone_name will return NULL and we will leave
* the setting as UNKNOWN. If this isn't overridden from the
* config file then pg_timezone_initialize() will eventually
* select a default value from the environment.
*/

...but that seems a few bricks short of a load, because it doesn't
handle this case properly.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company