This patch makes it possible to use the full set of timezones when doing

"AT TIME ZONE", and not just the shorlist previously available. For
example:

SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';

works fine now. It will also obey whatever DST rules were in effect at
just that date, which the previous implementation did not.

It also supports the AT TIME ZONE on the timetz datatype. The whole
handling of DST is a bit bogus there, so I chose to make it use whatever
DST rules are in effect at the time of executig the query. not sure if
anybody is actuallyi *using* timetz though, it seems pretty
unpredictable just because of this...

Magnus Hagander

7 files changed, 135 insertions, 118 deletions

diff --git a/src/backend/utils/adt/date.c b/src/backend/utils/adt/date.c
index 5371c64250a..abc6155594f 100644
--- a/src/backend/utils/adt/date.c
+++ b/src/backend/utils/adt/date.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.109 2005/05/26 02:04:13 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.110 2005/06/15 00:34:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,6 +18,7 @@
 #include <ctype.h>
 #include <limits.h>
 #include <float.h>
+#include <time.h> 
 
 #include "access/hash.h"
 #include "libpq/pqformat.h"
@@ -724,7 +725,7 @@ timestamp_date(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+	if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -767,7 +768,7 @@ timestamptz_date(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -1327,7 +1328,7 @@ timestamp_time(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+	if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -1364,7 +1365,7 @@ timestamptz_time(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -2247,7 +2248,7 @@ timestamptz_timetz(PG_FUNCTION_ARGS)
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+	if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -2463,53 +2464,60 @@ timetz_part(PG_FUNCTION_ARGS)
 
 /* timetz_zone()
  * Encode time with time zone type with specified time zone.
+ * Applies DST rules as of the current date.
  */
 Datum
 timetz_zone(PG_FUNCTION_ARGS)
 {
 	text	   *zone = PG_GETARG_TEXT_P(0);
-	TimeTzADT  *time = PG_GETARG_TIMETZADT_P(1);
+	TimeTzADT  *t = PG_GETARG_TIMETZADT_P(1);
 	TimeTzADT  *result;
 	int			tz;
-	int			type,
-				val;
-	char	   *lowzone;
-
-	lowzone = downcase_truncate_identifier(VARDATA(zone),
-										   VARSIZE(zone) - VARHDRSZ,
-										   false);
-
-	type = DecodeSpecial(0, lowzone, &val);
+	char        tzname[TZ_STRLEN_MAX];
+	int         len;
+	pg_tz	   *tzp;
+	struct pg_tm *tm;
+	pg_time_t   now;
+
+	/* Find the specified timezone */ 
+	len = (VARSIZE(zone)-VARHDRSZ>TZ_STRLEN_MAX)?TZ_STRLEN_MAX:(VARSIZE(zone)-VARHDRSZ);
+	memcpy(tzname,VARDATA(zone),len);
+	tzname[len]=0;
+	tzp = pg_tzset(tzname);
+	if (!tzp) {
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+		 	 errmsg("time zone \"%s\" not recognized", tzname)));
+		PG_RETURN_NULL();
+	}
 
-	result = (TimeTzADT *) palloc(sizeof(TimeTzADT));
+	/* Get the offset-from-GMT that is valid today for the selected zone */
+	if ((now = time(NULL)) < 0 ||
+	    (tm = pg_localtime(&now, tzp)) == NULL) {
+	   	ereport(ERROR,
+	   		(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("could not determine current time")));
+		PG_RETURN_NULL();
+	}
 
-	if (type == TZ || type == DTZ)
-	{
-		tz = val * 60;
+	result = (TimeTzADT *)palloc(sizeof(TimeTzADT));
+	
+	tz = -tm->tm_gmtoff;
 #ifdef HAVE_INT64_TIMESTAMP
-		result->time = time->time + (time->zone - tz) * USECS_PER_SEC;
-		while (result->time < INT64CONST(0))
-			result->time += USECS_PER_DAY;
-		while (result->time >= USECS_PER_DAY)
-			result->time -= USECS_PER_DAY;
+	result->time = t->time + (t->zone - tz) * USECS_PER_SEC;
+	while (result->time < INT64CONST(0))
+		result->time += USECS_PER_DAY;
+	while (result->time >= USECS_PER_DAY)
+		result->time -= USECS_PER_DAY;
 #else
-		result->time = time->time + (time->zone - tz);
-		while (result->time < 0)
-			result->time += SECS_PER_DAY;
-		while (result->time >= SECS_PER_DAY)
-			result->time -= SECS_PER_DAY;
+	result->time = t->time + (t->zone - tz);
+	while (result->time < 0)
+		result->time += SECS_PER_DAY;
+	while (result->time >= SECS_PER_DAY)
+		result->time -= SECS_PER_DAY;
 #endif
 
-		result->zone = tz;
-	}
-	else
-	{
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognized", lowzone)));
-
-		PG_RETURN_NULL();
-	}
+	result->zone = tz;
 
 	PG_RETURN_TIMETZADT_P(result);
 }	/* timetz_zone() */
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 68a73bbb6fc..e4de64444ea 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -1,7 +1,7 @@
 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.87 2005/05/25 21:40:40 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.88 2005/06/15 00:34:08 momjian Exp $
  *
  *
  *	 Portions Copyright (c) 1999-2005, PostgreSQL Global Development Group
@@ -2910,7 +2910,7 @@ timestamp_to_char(PG_FUNCTION_ARGS)
 
 	ZERO_tmtc(&tmtc);
 
-	if (timestamp2tm(dt, NULL, tmtcTm(&tmtc), &tmtcFsec(&tmtc), NULL) != 0)
+	if (timestamp2tm(dt, NULL, tmtcTm(&tmtc), &tmtcFsec(&tmtc), NULL, NULL) != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -2935,7 +2935,7 @@ timestamptz_to_char(PG_FUNCTION_ARGS)
 
 	ZERO_tmtc(&tmtc);
 
-	if (timestamp2tm(dt, &tz, tmtcTm(&tmtc), &tmtcFsec(&tmtc), &tmtcTzn(&tmtc)) != 0)
+	if (timestamp2tm(dt, &tz, tmtcTm(&tmtc), &tmtcFsec(&tmtc), &tmtcTzn(&tmtc), NULL) != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
diff --git a/src/backend/utils/adt/nabstime.c b/src/backend/utils/adt/nabstime.c
index bebd3f9d325..d712d9f8b46 100644
--- a/src/backend/utils/adt/nabstime.c
+++ b/src/backend/utils/adt/nabstime.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/nabstime.c,v 1.132 2005/05/26 02:04:13 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/nabstime.c,v 1.133 2005/06/15 00:34:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -556,7 +556,7 @@ timestamp_abstime(PG_FUNCTION_ARGS)
 		result = NOSTART_ABSTIME;
 	else if (TIMESTAMP_IS_NOEND(timestamp))
 		result = NOEND_ABSTIME;
-	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) == 0)
+	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) == 0)
 	{
 		tz = DetermineLocalTimeZone(tm);
 		result = tm2abstime(tm, tz);
@@ -632,7 +632,7 @@ timestamptz_abstime(PG_FUNCTION_ARGS)
 		result = NOSTART_ABSTIME;
 	else if (TIMESTAMP_IS_NOEND(timestamp))
 		result = NOEND_ABSTIME;
-	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) == 0)
+	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) == 0)
 		result = tm2abstime(tm, 0);
 	else
 	{
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 37308d7451a..035a422bfcc 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.125 2005/06/14 21:04:40 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.126 2005/06/15 00:34:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -142,7 +142,7 @@ timestamp_out(PG_FUNCTION_ARGS)
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		EncodeSpecialTimestamp(timestamp, buf);
-	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) == 0)
+	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) == 0)
 		EncodeDateTime(tm, fsec, NULL, &tzn, DateStyle, buf);
 	else
 		ereport(ERROR,
@@ -178,7 +178,7 @@ timestamp_recv(PG_FUNCTION_ARGS)
 	/* rangecheck: see if timestamp_out would like it */
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		 /* ok */ ;
-	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+	else if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -381,7 +381,7 @@ timestamptz_out(PG_FUNCTION_ARGS)
 
 	if (TIMESTAMP_NOT_FINITE(dt))
 		EncodeSpecialTimestamp(dt, buf);
-	else if (timestamp2tm(dt, &tz, tm, &fsec, &tzn) == 0)
+	else if (timestamp2tm(dt, &tz, tm, &fsec, &tzn, NULL) == 0)
 		EncodeDateTime(tm, fsec, &tz, &tzn, DateStyle, buf);
 	else
 		ereport(ERROR,
@@ -419,7 +419,7 @@ timestamptz_recv(PG_FUNCTION_ARGS)
 	/* rangecheck: see if timestamptz_out would like it */
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		 /* ok */ ;
-	else if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+	else if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("timestamp out of range")));
@@ -984,9 +984,12 @@ dt2time(Timestamp jd, int *hour, int *min, int *sec, fsec_t *fsec)
  * Returns:
  *	 0 on success
  *	-1 on out of range
+ *
+ * If attimezone is NULL, the global timezone (including possblly brute forced
+ * timezone) will be used.
  */
 int
-timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn)
+timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn, pg_tz *attimezone)
 {
 	Timestamp date;
 	Timestamp	time;
@@ -997,7 +1000,7 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn
 	 * specified. Go ahead and rotate to the local time zone since we will
 	 * later bypass any calls which adjust the tm fields.
 	 */
-	if (HasCTZSet && (tzp != NULL))
+	if ((attimezone==NULL) && HasCTZSet && (tzp != NULL))
 	{
 #ifdef HAVE_INT64_TIMESTAMP
 		dt -= CTimeZone * USECS_PER_SEC;
@@ -1050,7 +1053,7 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn
 	 * We have a brute force time zone per SQL99? Then use it without
 	 * change since we have already rotated to the time zone.
 	 */
-	if (HasCTZSet)
+	if ((attimezone==NULL) && HasCTZSet)
 	{
 		*tzp = CTimeZone;
 		tm->tm_isdst = 0;
@@ -1081,7 +1084,7 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn
 	utime = (pg_time_t) dt;
 	if ((Timestamp) utime == dt)
 	{
-		struct pg_tm *tx = pg_localtime(&utime, global_timezone);
+		struct pg_tm *tx = pg_localtime(&utime, (attimezone!=NULL)?attimezone:global_timezone);
 
 		tm->tm_year = tx->tm_year + 1900;
 		tm->tm_mon = tx->tm_mon + 1;
@@ -1926,7 +1929,7 @@ timestamp_pl_interval(PG_FUNCTION_ARGS)
 					   *tm = &tt;
 			fsec_t		fsec;
 
-			if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+			if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 						 errmsg("timestamp out of range")));
@@ -2005,7 +2008,7 @@ timestamptz_pl_interval(PG_FUNCTION_ARGS)
 					   *tm = &tt;
 			fsec_t		fsec;
 
-			if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+			if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 						 errmsg("timestamp out of range")));
@@ -2332,8 +2335,8 @@ timestamp_age(PG_FUNCTION_ARGS)
 
 	result = (Interval *) palloc(sizeof(Interval));
 
-	if (timestamp2tm(dt1, NULL, tm1, &fsec1, NULL) == 0 &&
-		timestamp2tm(dt2, NULL, tm2, &fsec2, NULL) == 0)
+	if (timestamp2tm(dt1, NULL, tm1, &fsec1, NULL, NULL) == 0 &&
+		timestamp2tm(dt2, NULL, tm2, &fsec2, NULL, NULL) == 0)
 	{
 		fsec = (fsec1 - fsec2);
 		tm->tm_sec = tm1->tm_sec - tm2->tm_sec;
@@ -2446,8 +2449,8 @@ timestamptz_age(PG_FUNCTION_ARGS)
 
 	result = (Interval *) palloc(sizeof(Interval));
 
-	if (timestamp2tm(dt1, &tz1, tm1, &fsec1, &tzn) == 0 &&
-		timestamp2tm(dt2, &tz2, tm2, &fsec2, &tzn) == 0)
+	if (timestamp2tm(dt1, &tz1, tm1, &fsec1, &tzn, NULL) == 0 &&
+		timestamp2tm(dt2, &tz2, tm2, &fsec2, &tzn, NULL) == 0)
 	{
 		fsec = fsec1 - fsec2;
 		tm->tm_sec = tm1->tm_sec - tm2->tm_sec;
@@ -2750,7 +2753,7 @@ timestamp_trunc(PG_FUNCTION_ARGS)
 
 	if (type == UNITS)
 	{
-		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -2881,7 +2884,7 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
 
 	if (type == UNITS)
 	{
-		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -3271,7 +3274,7 @@ timestamp_part(PG_FUNCTION_ARGS)
 
 	if (type == UNITS)
 	{
-		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -3405,7 +3408,7 @@ timestamp_part(PG_FUNCTION_ARGS)
 					 * convert to timestamptz to produce consistent
 					 * results
 					 */
-					if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+					if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 						ereport(ERROR,
 						   (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							errmsg("timestamp out of range")));
@@ -3425,7 +3428,7 @@ timestamp_part(PG_FUNCTION_ARGS)
 					break;
 				}
 			case DTK_DOW:
-				if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+				if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
@@ -3433,7 +3436,7 @@ timestamp_part(PG_FUNCTION_ARGS)
 				break;
 
 			case DTK_DOY:
-				if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+				if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
@@ -3496,7 +3499,7 @@ timestamptz_part(PG_FUNCTION_ARGS)
 
 	if (type == UNITS)
 	{
-		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -3631,7 +3634,7 @@ timestamptz_part(PG_FUNCTION_ARGS)
 				break;
 
 			case DTK_DOW:
-				if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+				if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
@@ -3639,7 +3642,7 @@ timestamptz_part(PG_FUNCTION_ARGS)
 				break;
 
 			case DTK_DOY:
-				if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+				if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
@@ -3815,38 +3818,40 @@ timestamp_zone(PG_FUNCTION_ARGS)
 {
 	text	   *zone = PG_GETARG_TEXT_P(0);
 	Timestamp timestamp = PG_GETARG_TIMESTAMP(1);
-	TimestampTz result;
+	Timestamp result;
 	int			tz;
-	int			type,
-				val;
-	char	   *lowzone;
+	pg_tz      *tzp;
+	char        tzname[TZ_STRLEN_MAX+1];
+	int         len;
+	struct pg_tm tm;
+	fsec_t      fsec;
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMPTZ(timestamp);
 
-	lowzone = downcase_truncate_identifier(VARDATA(zone),
-										   VARSIZE(zone) - VARHDRSZ,
-										   false);
-
-	type = DecodeSpecial(0, lowzone, &val);
-
-	if (type == TZ || type == DTZ)
-	{
-		tz = -(val * 60);
-
-		result = dt2local(timestamp, tz);
-	}
-	else
-	{
+	/* Find the specified timezone? */
+	len = (VARSIZE(zone)-VARHDRSZ>TZ_STRLEN_MAX)?TZ_STRLEN_MAX:(VARSIZE(zone)-VARHDRSZ);
+	memcpy(tzname,VARDATA(zone),len);
+	tzname[len] = 0;
+	tzp = pg_tzset(tzname);
+	if (!tzp) {
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognized",
-						lowzone)));
-
+				 errmsg("time zone \"%s\" not recognised",
+				        tzname)));
 		PG_RETURN_NULL();
 	}
 
-	PG_RETURN_TIMESTAMPTZ(result);
+	/* Apply the timezone change */
+	if (timestamp2tm(timestamp, &tz, &tm, &fsec, NULL, tzp) != 0 ||
+	    tm2timestamp(&tm, fsec, NULL, &result) != 0) {
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("could not convert to time zone \"%s\"",
+				        tzname)));
+		PG_RETURN_NULL();
+	}
+	PG_RETURN_TIMESTAMPTZ(timestamp2timestamptz(result));
 }	/* timestamp_zone() */
 
 /* timestamp_izone()
@@ -3906,7 +3911,7 @@ timestamp2timestamptz(Timestamp timestamp)
 
 	else
 	{
-		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL) !=0)
+		if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -3941,7 +3946,7 @@ timestamptz_timestamp(PG_FUNCTION_ARGS)
 
 	else
 	{
-		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn) !=0)
+		if (timestamp2tm(timestamp, &tz, tm, &fsec, &tzn, NULL) !=0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
@@ -3950,7 +3955,6 @@ timestamptz_timestamp(PG_FUNCTION_ARGS)
 					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 					 errmsg("timestamp out of range")));
 	}
-
 	PG_RETURN_TIMESTAMP(result);
 }
 
@@ -3966,31 +3970,34 @@ timestamptz_zone(PG_FUNCTION_ARGS)
 	Timestamp	result;
 
 	int			tz;
-	int			type,
-				val;
-	char	   *lowzone;
+	pg_tz	   *tzp;
+	char        tzname[TZ_STRLEN_MAX];
+	int         len;
+	struct pg_tm tm;
+	fsec_t      fsec = 0;
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_NULL();
 
-	lowzone = downcase_truncate_identifier(VARDATA(zone),
-										   VARSIZE(zone) - VARHDRSZ,
-										   false);
-
-	type = DecodeSpecial(0, lowzone, &val);
+	/* Find the specified zone */
+	len = (VARSIZE(zone)-VARHDRSZ>TZ_STRLEN_MAX)?TZ_STRLEN_MAX:(VARSIZE(zone)-VARHDRSZ);
+	memcpy(tzname,VARDATA(zone),len);
+	tzname[len] = 0;
+	tzp = pg_tzset(tzname);
 
-	if (type == TZ || type == DTZ)
-	{
-		tz = val * 60;
+	if (!tzp) {
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("time zone \"%s\" not recognized", tzname)));
 
-		result = dt2local(timestamp, tz);
+		PG_RETURN_NULL();
 	}
-	else
-	{
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognized", lowzone)));
 
+	if (timestamp2tm(timestamp, &tz, &tm, &fsec, NULL, tzp) != 0 ||
+	    tm2timestamp(&tm, fsec, NULL, &result)) { 
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("could not to convert to time zone \"%s\"", tzname)));
 		PG_RETURN_NULL();
 	}
 
diff --git a/src/include/pgtime.h b/src/include/pgtime.h
index b3322234e19..c36a871fb33 100644
--- a/src/include/pgtime.h
+++ b/src/include/pgtime.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/include/pgtime.h,v 1.7 2005/04/19 03:13:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/include/pgtime.h,v 1.8 2005/06/15 00:34:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,4 +57,8 @@ extern bool tz_acceptable(pg_tz *tz);
 extern const char *pg_get_timezone_name(pg_tz *tz);
 
 extern pg_tz *global_timezone;
+
+/* Maximum length of a timezone name */
+#define TZ_STRLEN_MAX 255
+
 #endif   /* _PGTIME_H */
diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h
index 782b75ec8df..7475dacbe7c 100644
--- a/src/include/utils/timestamp.h
+++ b/src/include/utils/timestamp.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/timestamp.h,v 1.44 2005/06/14 21:04:42 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/timestamp.h,v 1.45 2005/06/15 00:34:10 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -264,7 +264,7 @@ extern TimestampTz StartTime;
 
 extern int	tm2timestamp(struct pg_tm * tm, fsec_t fsec, int *tzp, Timestamp *dt);
 extern int timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm,
-			 fsec_t *fsec, char **tzn);
+			 fsec_t *fsec, char **tzn, pg_tz *attimezone);
 extern void dt2time(Timestamp dt, int *hour, int *min, int *sec, fsec_t *fsec);
 
 extern int	interval2tm(Interval span, struct pg_tm * tm, fsec_t *fsec);
diff --git a/src/timezone/pgtz.h b/src/timezone/pgtz.h
index e325dec4832..a6e6bbf97f6 100644
--- a/src/timezone/pgtz.h
+++ b/src/timezone/pgtz.h
@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/timezone/pgtz.h,v 1.11 2005/04/19 03:13:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/timezone/pgtz.h,v 1.12 2005/06/15 00:34:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,8 +18,6 @@
 
 #include "tzfile.h"
 
-#define TZ_STRLEN_MAX 255
-
 extern char *pg_TZDIR(void);
 
 #define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))