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
2025-09-02 04:21:28 +03:00 · 2005-06-15 00:34:11 +00:00
parent 5955945828
commit 0851a6fbc7
9 changed files with 145 additions and 129 deletions
--- 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")));
@@ -2463,54 +2464,61 @@ 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;
+	char        tzname[TZ_STRLEN_MAX];
+	int         len;
+	pg_tz	   *tzp;
+	struct pg_tm *tm;
+	pg_time_t   now;

-	lowzone = downcase_truncate_identifier(VARDATA(zone),
-										   VARSIZE(zone) - VARHDRSZ,
-										   false);
-
-	type = DecodeSpecial(0, lowzone, &val);
-
-	result = (TimeTzADT *) palloc(sizeof(TimeTzADT));
-
-	if (type == TZ || type == DTZ)
-	{
-		tz = val * 60;
-#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;
-#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;
-#endif
-
-		result->zone = 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)));
-
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+		 	 errmsg("time zone \"%s\" not recognized", tzname)));
 		PG_RETURN_NULL();
 	}

+	/* 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();
+	}
+
+	result = (TimeTzADT *)palloc(sizeof(TimeTzADT));
+	
+	tz = -tm->tm_gmtoff;
+#ifdef HAVE_INT64_TIMESTAMP
+	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 = 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;
+
 	PG_RETURN_TIMETZADT_P(result);
 }	/* timetz_zone() */

--- 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")));
--- 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
 	{
--- 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);
 }

@@ -3966,34 +3970,37 @@ 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);
+	/* 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);

-	type = DecodeSpecial(0, lowzone, &val);
-
-	if (type == TZ || type == DTZ)
-	{
-		tz = val * 60;
-
-		result = dt2local(timestamp, tz);
-	}
-	else
-	{
+	if (!tzp) {
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognized", lowzone)));
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("time zone \"%s\" not recognized", tzname)));

 		PG_RETURN_NULL();
 	}

+	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();
+	}
+
 	PG_RETURN_TIMESTAMP(result);
 }	/* timestamptz_zone() */

--- 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 */
--- 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);
--- 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))