Remove CTimeZone/HasCTZSet, root and branch.

These variables no longer have any useful purpose, since there's no reason
to special-case brute force timezones now that we have a valid
session_timezone setting for them.  Remove the variables, and remove the
SET/SHOW TIME ZONE code that deals with them.

The user-visible impact of this is that SHOW TIME ZONE will now show a
POSIX-style zone specification, in the form "<+-offset>-+offset", rather
than an interval value when a brute-force zone has been set.  While perhaps
less intuitive, this is a better definition than before because it's
actually possible to give that string back to SET TIME ZONE and get the
same behavior, unlike what used to happen.

We did not previously mention the angle-bracket syntax when describing
POSIX timezone specifications; add some documentation so that people
can figure out what these strings do.  (There's still quite a lot of
undocumented functionality there, but anybody who really cares can
go read the POSIX spec to find out about it.  In practice most people
seem to prefer Olsen-style city names anyway.)

1 files changed, 14 insertions, 82 deletions

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index b6af6e7e253..e1ce6ff5b0a 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -243,34 +243,17 @@ assign_datestyle(const char *newval, void *extra)
  * TIMEZONE
  */
 
-typedef struct
-{
-	pg_tz	   *session_timezone;
-	int			CTimeZone;
-	bool		HasCTZSet;
-} timezone_extra;
-
 /*
  * check_timezone: GUC check_hook for timezone
  */
 bool
 check_timezone(char **newval, void **extra, GucSource source)
 {
-	timezone_extra myextra;
+	pg_tz	   *new_tz;
+	long		gmtoffset;
 	char	   *endptr;
 	double		hours;
 
-	/*
-	 * Initialize the "extra" struct that will be passed to assign_timezone.
-	 * We don't want to change any of the three global variables except as
-	 * specified by logic below.  To avoid leaking memory during failure
-	 * returns, we set up the struct contents in a local variable, and only
-	 * copy it to *extra at the end.
-	 */
-	myextra.session_timezone = session_timezone;
-	myextra.CTimeZone = CTimeZone;
-	myextra.HasCTZSet = HasCTZSet;
-
 	if (pg_strncasecmp(*newval, "interval", 8) == 0)
 	{
 		/*
@@ -323,12 +306,11 @@ check_timezone(char **newval, void **extra, GucSource source)
 
 		/* Here we change from SQL to Unix sign convention */
 #ifdef HAVE_INT64_TIMESTAMP
-		myextra.CTimeZone = -(interval->time / USECS_PER_SEC);
+		gmtoffset = -(interval->time / USECS_PER_SEC);
 #else
-		myextra.CTimeZone = -interval->time;
+		gmtoffset = -interval->time;
 #endif
-		myextra.session_timezone = pg_tzset_offset(myextra.CTimeZone);
-		myextra.HasCTZSet = true;
+		new_tz = pg_tzset_offset(gmtoffset);
 
 		pfree(interval);
 	}
@@ -341,17 +323,14 @@ check_timezone(char **newval, void **extra, GucSource source)
 		if (endptr != *newval && *endptr == '\0')
 		{
 			/* Here we change from SQL to Unix sign convention */
-			myextra.CTimeZone = -hours * SECS_PER_HOUR;
-			myextra.session_timezone = pg_tzset_offset(myextra.CTimeZone);
-			myextra.HasCTZSet = true;
+			gmtoffset = -hours * SECS_PER_HOUR;
+			new_tz = pg_tzset_offset(gmtoffset);
 		}
 		else
 		{
 			/*
 			 * Otherwise assume it is a timezone name, and try to load it.
 			 */
-			pg_tz	   *new_tz;
-
 			new_tz = pg_tzset(*newval);
 
 			if (!new_tz)
@@ -367,40 +346,16 @@ check_timezone(char **newval, void **extra, GucSource source)
 				GUC_check_errdetail("PostgreSQL does not support leap seconds.");
 				return false;
 			}
-
-			myextra.session_timezone = new_tz;
-			myextra.HasCTZSet = false;
 		}
 	}
 
 	/*
-	 * Prepare the canonical string to return.	GUC wants it malloc'd.
-	 *
-	 * Note: the result string should be something that we'd accept as input.
-	 * We use the numeric format for interval cases, because it's simpler to
-	 * reload.	In the named-timezone case, *newval is already OK and need not
-	 * be changed; it might not have the canonical casing, but that's taken
-	 * care of by show_timezone.
-	 */
-	if (myextra.HasCTZSet)
-	{
-		char	   *result = (char *) malloc(64);
-
-		if (!result)
-			return false;
-		snprintf(result, 64, "%.5f",
-				 (double) (-myextra.CTimeZone) / (double) SECS_PER_HOUR);
-		free(*newval);
-		*newval = result;
-	}
-
-	/*
 	 * Pass back data for assign_timezone to use
 	 */
-	*extra = malloc(sizeof(timezone_extra));
+	*extra = malloc(sizeof(pg_tz *));
 	if (!*extra)
 		return false;
-	memcpy(*extra, &myextra, sizeof(timezone_extra));
+	*((pg_tz **) *extra) = new_tz;
 
 	return true;
 }
@@ -411,43 +366,19 @@ check_timezone(char **newval, void **extra, GucSource source)
 void
 assign_timezone(const char *newval, void *extra)
 {
-	timezone_extra *myextra = (timezone_extra *) extra;
-
-	session_timezone = myextra->session_timezone;
-	CTimeZone = myextra->CTimeZone;
-	HasCTZSet = myextra->HasCTZSet;
+	session_timezone = *((pg_tz **) extra);
 }
 
 /*
  * show_timezone: GUC show_hook for timezone
- *
- * We wouldn't need this, except that historically interval values have been
- * shown without an INTERVAL prefix, so the display format isn't what would
- * be accepted as input.  Otherwise we could have check_timezone return the
- * preferred string to begin with.
  */
 const char *
 show_timezone(void)
 {
 	const char *tzn;
 
-	if (HasCTZSet)
-	{
-		Interval	interval;
-
-		interval.month = 0;
-		interval.day = 0;
-#ifdef HAVE_INT64_TIMESTAMP
-		interval.time = -(CTimeZone * USECS_PER_SEC);
-#else
-		interval.time = -CTimeZone;
-#endif
-
-		tzn = DatumGetCString(DirectFunctionCall1(interval_out,
-											  IntervalPGetDatum(&interval)));
-	}
-	else
-		tzn = pg_get_timezone_name(session_timezone);
+	/* Always show the zone's canonical name */
+	tzn = pg_get_timezone_name(session_timezone);
 
 	if (tzn != NULL)
 		return tzn;
@@ -497,7 +428,7 @@ check_log_timezone(char **newval, void **extra, GucSource source)
 	*extra = malloc(sizeof(pg_tz *));
 	if (!*extra)
 		return false;
-	memcpy(*extra, &new_tz, sizeof(pg_tz *));
+	*((pg_tz **) *extra) = new_tz;
 
 	return true;
 }
@@ -519,6 +450,7 @@ show_log_timezone(void)
 {
 	const char *tzn;
 
+	/* Always show the zone's canonical name */
 	tzn = pg_get_timezone_name(log_timezone);
 
 	if (tzn != NULL)