diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index eebc59172b..90fd253d0c 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -4940,6 +4940,177 @@ timestamptz_trunc_zone(PG_FUNCTION_ARGS)
 	PG_RETURN_TIMESTAMPTZ(result);
 }
 
+/*
+ * Common code for timestamptz_trunc_int() and timestamptz_trunc_int_zone().
+ *
+ * tzp identifies the zone to truncate with respect to.  We assume
+ * infinite timestamps have already been rejected.
+ */
+static TimestampTz
+timestamptz_trunc_int_internal(Interval *interval, TimestampTz timestamp, pg_tz *tzp)
+{
+	TimestampTz result;
+	int			tz;
+	int			interval_parts = 0;
+	bool		bad_interval = false;
+	bool		redotz = false;
+	fsec_t		fsec;
+	struct pg_tm tt,
+			   *tm = &tt;
+
+	if (interval->month != 0)
+	{
+		interval_parts++;
+		/* 1200 = hundred years */
+		if ((1200/interval->month) * interval->month != 1200)
+			bad_interval = true;
+	}
+	if (interval->day != 0)
+	{
+		interval_parts++;
+		if (interval->day != 1 && interval->day != 7)
+			bad_interval = true;
+	}
+	if (interval->time != 0)
+	{
+		interval_parts++;
+		if (interval->time > USECS_PER_SEC)
+		{
+			if ((interval->time % USECS_PER_SEC) != 0)
+				bad_interval = true;
+			if ((USECS_PER_DAY/interval->time) * interval->time != USECS_PER_DAY)
+				bad_interval = true;
+		}
+		else if (interval->time < USECS_PER_SEC && (USECS_PER_SEC/interval->time) * interval->time != USECS_PER_SEC)
+			bad_interval = true;
+	}
+	if (interval_parts != 1 || bad_interval)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("interval has to be a divisor of a day, week or century.")));
+		return 0;
+	}
+
+	if (timestamp2tm(timestamp, &tz, tm, &fsec, NULL, tzp) != 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+				 errmsg("timestamp out of range")));
+
+	if (interval->month != 0)
+	{
+		int			months;
+		months = (tm->tm_year - 1) * 12 + tm->tm_mon - 1;
+		months -= months % interval->month;
+		tm->tm_year = (months / 12) + 1;
+		tm->tm_mon = (months % 12) + 1;
+		tm->tm_mday = 1;
+		tm->tm_hour = 0;
+		tm->tm_min = 0;
+		tm->tm_sec = 0;
+		fsec = 0;
+		redotz = true;
+	}
+	else if (interval->day == 7)
+	{
+		int			woy;
+		woy = date2isoweek(tm->tm_year, tm->tm_mon, tm->tm_mday);
+
+		/*
+		 * If it is week 52/53 and the month is January, then the
+		 * week must belong to the previous year. Also, some
+		 * December dates belong to the next year.
+		 */
+		if (woy >= 52 && tm->tm_mon == 1)
+			--tm->tm_year;
+		if (woy <= 1 && tm->tm_mon == MONTHS_PER_YEAR)
+			++tm->tm_year;
+		isoweek2date(woy, &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
+		tm->tm_hour = 0;
+		tm->tm_min = 0;
+		tm->tm_sec = 0;
+		fsec = 0;
+		redotz = true;
+	}
+	else if (interval->day == 1)
+	{
+		tm->tm_hour = 0;
+		tm->tm_min = 0;
+		tm->tm_sec = 0;
+		fsec = 0;
+		redotz = true;	/* for all cases > HOUR */
+	}
+	else if (interval->time > USECS_PER_SEC)
+	{
+		int			seconds;
+		seconds = tm->tm_hour * 3600 + tm->tm_min * 60 + tm->tm_sec;
+		seconds -= seconds % (interval->time / USECS_PER_SEC);
+		tm->tm_hour = seconds / 3600;
+		tm->tm_min = (seconds / 60) % 60;
+		tm->tm_sec = seconds % 60;
+		fsec = 0;
+		redotz = (interval->time > USECS_PER_HOUR);
+	}
+	else if (interval->time == USECS_PER_SEC)
+		fsec = 0;
+	else if (interval->time > 0)
+		fsec -= fsec % interval->time;
+
+	if (redotz)
+		tz = DetermineTimeZoneOffset(tm, tzp);
+
+	if (tm2timestamp(tm, fsec, &tz, &result) != 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+				 errmsg("timestamp out of range")));
+
+	return result;
+}
+
+/* timestamptz_trunc_int()
+ * Truncate timestamptz to specified interval in session timezone.
+ */
+Datum
+timestamptz_trunc_int(PG_FUNCTION_ARGS)
+{
+	Interval   *interval = PG_GETARG_INTERVAL_P(0);
+	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
+	TimestampTz result;
+
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMPTZ(timestamp);
+
+	result = timestamptz_trunc_int_internal(interval, timestamp, session_timezone);
+
+	PG_RETURN_TIMESTAMPTZ(result);
+}
+
+/* timestamptz_trunc_zone()
+ * Truncate timestamptz to specified interval in specified timezone.
+ */
+Datum
+timestamptz_trunc_int_zone(PG_FUNCTION_ARGS)
+{
+	Interval   *interval = PG_GETARG_INTERVAL_P(0);
+	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
+	text	   *zone = PG_GETARG_TEXT_PP(2);
+	TimestampTz result;
+	pg_tz	   *tzp;
+
+	/*
+	 * timestamptz_zone() doesn't look up the zone for infinite inputs, so we
+	 * don't do so here either.
+	 */
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMP(timestamp);
+
+	tzp = lookup_timezone(zone);
+
+	result = timestamptz_trunc_int_internal(interval, timestamp, tzp);
+
+	PG_RETURN_TIMESTAMPTZ(result);
+}
+
 /* interval_trunc()
  * Extract specified field from interval.
  */
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index b8b26c263d..01393a4d4f 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -2481,6 +2481,14 @@
 { oid => '1218', descr => 'truncate interval to specified units',
   proname => 'date_trunc', prorettype => 'interval',
   proargtypes => 'text interval', prosrc => 'interval_trunc' },
+{ oid => '8802',
+  descr => 'truncate timestamp with time zone to specified interval',
+  proname => 'date_trunc', provolatile => 's', prorettype => 'timestamptz',
+  proargtypes => 'interval timestamptz', prosrc => 'timestamptz_trunc_int' },
+{ oid => '8803',
+  descr => 'truncate timestamp with time zone to specified interval in specified time zone',
+  proname => 'date_trunc', prorettype => 'timestamptz',
+  proargtypes => 'interval timestamptz text', prosrc => 'timestamptz_trunc_int_zone' },
 
 { oid => '1219', descr => 'increment',
   proname => 'int8inc', prorettype => 'int8', proargtypes => 'int8',
diff --git a/src/test/regress/expected/timestamptz.out b/src/test/regress/expected/timestamptz.out
index a084357480..c799ba224b 100644
--- a/src/test/regress/expected/timestamptz.out
+++ b/src/test/regress/expected/timestamptz.out
@@ -695,7 +695,7 @@ SELECT d1 - timestamp with time zone '1997-01-02' AS diff
  @ 1460 days 17 hours 32 mins 1 sec
 (56 rows)
 
-SELECT date_trunc( 'week', timestamp with time zone '2004-02-29 15:44:17.71393' ) AS week_trunc;
+SELECT date_trunc('week', timestamp with time zone '2004-02-29 15:44:17.71393') AS week_trunc;
           week_trunc          
 ------------------------------
  Mon Feb 23 00:00:00 2004 PST
@@ -719,11 +719,67 @@ SELECT date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'VET
  Thu Feb 15 20:00:00 2001 PST
 (1 row)
 
+SELECT date_trunc('7 day'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS week_trunc;
+          week_trunc          
+------------------------------
+ Mon Feb 23 00:00:00 2004 PST
+(1 row)
+
+SELECT date_trunc('3 month'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Australia/Sydney') as sydney_trunc;  -- zone name
+         sydney_trunc         
+------------------------------
+ Sun Dec 31 05:00:00 2000 PST
+(1 row)
+
+SELECT date_trunc('12 hour'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'GMT') as gmt_trunc;  -- fixed-offset abbreviation
+          gmt_trunc           
+------------------------------
+ Fri Feb 16 04:00:00 2001 PST
+(1 row)
+
+SELECT date_trunc('6 hour'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc;  -- variable-offset abbreviation
+          vet_trunc           
+------------------------------
+ Fri Feb 16 08:00:00 2001 PST
+(1 row)
+
+SELECT date_trunc('6 minutes'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc;  -- variable-offset abbreviation
+          vet_trunc           
+------------------------------
+ Fri Feb 16 12:36:00 2001 PST
+(1 row)
+
+SELECT date_trunc('10 second'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS tensec_trunc;
+         tensec_trunc         
+------------------------------
+ Sun Feb 29 15:44:10 2004 PST
+(1 row)
+
+SELECT date_trunc('500 msecond'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS halfsec_trunc;
+         halfsec_trunc          
+--------------------------------
+ Sun Feb 29 15:44:17.5 2004 PST
+(1 row)
+
+-- errors
+SELECT date_trunc('1 month 7 day'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval1;
+ERROR:  interval has to be a divisor of a day, week or century.
+SELECT date_trunc('1 month 01:00:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval2;
+ERROR:  interval has to be a divisor of a day, week or century.
+SELECT date_trunc('1 day 00:30:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval3;
+ERROR:  interval has to be a divisor of a day, week or century.
+SELECT date_trunc('7 month'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval4;
+ERROR:  interval has to be a divisor of a day, week or century.
+SELECT date_trunc('3 day'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval5;
+ERROR:  interval has to be a divisor of a day, week or century.
+SELECT date_trunc('00:23:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval6;
+ERROR:  interval has to be a divisor of a day, week or century.
 -- verify date_bin behaves the same as date_trunc for relevant intervals
 SELECT
   str,
   interval,
-  date_trunc(str, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal
+  date_trunc(str, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal_str,
+  date_trunc(interval::interval, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal_interval
 FROM (
   VALUES
   ('day', '1 d'),
@@ -734,14 +790,14 @@ FROM (
   ('microsecond', '1 us')
 ) intervals (str, interval),
 (VALUES (timestamptz '2020-02-29 15:44:17.71393+00')) ts (ts);
-     str     | interval | equal 
--------------+----------+-------
- day         | 1 d      | t
- hour        | 1 h      | t
- minute      | 1 m      | t
- second      | 1 s      | t
- millisecond | 1 ms     | t
- microsecond | 1 us     | t
+     str     | interval | equal_str | equal_interval 
+-------------+----------+-----------+----------------
+ day         | 1 d      | t         | t
+ hour        | 1 h      | t         | t
+ minute      | 1 m      | t         | t
+ second      | 1 s      | t         | t
+ millisecond | 1 ms     | t         | t
+ microsecond | 1 us     | t         | t
 (6 rows)
 
 -- bin timestamps into arbitrary intervals
@@ -2525,6 +2581,75 @@ SELECT * FROM generate_series('2021-12-31 23:00:00+00'::timestamptz,
  Thu Dec 31 23:00:00 2020 UTC
 (13 rows)
 
+SET TimeZone to 'Europe/Warsaw';
+-- DST - 23 hours in day
+SELECT ts,
+       date_trunc('1 hour'::interval, ts, 'Europe/Warsaw') AS one_hour_bin,
+       date_trunc('2 hour'::interval, ts, 'Europe/Warsaw') AS two_hours_bin,
+       date_trunc('3 hour'::interval, ts, 'Europe/Warsaw') AS three_hours_bin
+   FROM generate_series('2022-03-26 21:00:00+00'::timestamptz,
+                        '2022-03-27 07:00:00+00'::timestamptz,
+                        '30 min'::interval,
+                        'Europe/Warsaw') AS ts;
+              ts               |         one_hour_bin          |         two_hours_bin         |        three_hours_bin        
+-------------------------------+-------------------------------+-------------------------------+-------------------------------
+ Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 21:00:00 2022 CET
+ Sat Mar 26 22:30:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 21:00:00 2022 CET
+ Sat Mar 26 23:00:00 2022 CET  | Sat Mar 26 23:00:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 21:00:00 2022 CET
+ Sat Mar 26 23:30:00 2022 CET  | Sat Mar 26 23:00:00 2022 CET  | Sat Mar 26 22:00:00 2022 CET  | Sat Mar 26 21:00:00 2022 CET
+ Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET
+ Sun Mar 27 00:30:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET
+ Sun Mar 27 01:00:00 2022 CET  | Sun Mar 27 01:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET
+ Sun Mar 27 01:30:00 2022 CET  | Sun Mar 27 01:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET  | Sun Mar 27 00:00:00 2022 CET
+ Sun Mar 27 03:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 03:30:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 04:30:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 05:00:00 2022 CEST | Sun Mar 27 05:00:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 05:30:00 2022 CEST | Sun Mar 27 05:00:00 2022 CEST | Sun Mar 27 04:00:00 2022 CEST | Sun Mar 27 03:00:00 2022 CEST
+ Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 06:30:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 07:00:00 2022 CEST | Sun Mar 27 07:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 07:30:00 2022 CEST | Sun Mar 27 07:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 08:30:00 2022 CEST | Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 06:00:00 2022 CEST
+ Sun Mar 27 09:00:00 2022 CEST | Sun Mar 27 09:00:00 2022 CEST | Sun Mar 27 08:00:00 2022 CEST | Sun Mar 27 09:00:00 2022 CEST
+(21 rows)
+
+-- DST - 25 hours in day
+SELECT ts,
+       date_trunc('1 hour'::interval, ts, 'Europe/Warsaw') AS one_hour_bin,
+       date_trunc('2 hour'::interval, ts, 'Europe/Warsaw') AS two_hours_bin,
+       date_trunc('3 hour'::interval, ts, 'Europe/Warsaw') AS three_hours_bin
+   FROM generate_series('2022-10-29 21:00:00+00'::timestamptz,
+                        '2022-10-30 07:00:00+00'::timestamptz,
+                        '30 min'::interval,
+                        'Europe/Warsaw') AS ts;
+              ts               |         one_hour_bin          |         two_hours_bin         |        three_hours_bin        
+-------------------------------+-------------------------------+-------------------------------+-------------------------------
+ Sat Oct 29 23:00:00 2022 CEST | Sat Oct 29 23:00:00 2022 CEST | Sat Oct 29 22:00:00 2022 CEST | Sat Oct 29 21:00:00 2022 CEST
+ Sat Oct 29 23:30:00 2022 CEST | Sat Oct 29 23:00:00 2022 CEST | Sat Oct 29 22:00:00 2022 CEST | Sat Oct 29 21:00:00 2022 CEST
+ Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 00:30:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 01:00:00 2022 CEST | Sun Oct 30 01:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 01:30:00 2022 CEST | Sun Oct 30 01:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 02:00:00 2022 CEST | Sun Oct 30 02:00:00 2022 CEST | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 02:30:00 2022 CEST | Sun Oct 30 02:00:00 2022 CEST | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 02:30:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 00:00:00 2022 CEST
+ Sun Oct 30 03:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 03:30:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET  | Sun Oct 30 02:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 04:30:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 05:00:00 2022 CET  | Sun Oct 30 05:00:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 05:30:00 2022 CET  | Sun Oct 30 05:00:00 2022 CET  | Sun Oct 30 04:00:00 2022 CET  | Sun Oct 30 03:00:00 2022 CET
+ Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET
+ Sun Oct 30 06:30:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET
+ Sun Oct 30 07:00:00 2022 CET  | Sun Oct 30 07:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET
+ Sun Oct 30 07:30:00 2022 CET  | Sun Oct 30 07:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET
+ Sun Oct 30 08:00:00 2022 CET  | Sun Oct 30 08:00:00 2022 CET  | Sun Oct 30 08:00:00 2022 CET  | Sun Oct 30 06:00:00 2022 CET
+(21 rows)
+
 RESET TimeZone;
 --
 -- Test behavior with a dynamic (time-varying) timezone abbreviation.
diff --git a/src/test/regress/sql/timestamptz.sql b/src/test/regress/sql/timestamptz.sql
index a2dcd5f5d8..f7941e48b4 100644
--- a/src/test/regress/sql/timestamptz.sql
+++ b/src/test/regress/sql/timestamptz.sql
@@ -199,17 +199,33 @@ SELECT d1 FROM TIMESTAMPTZ_TBL
 SELECT d1 - timestamp with time zone '1997-01-02' AS diff
    FROM TIMESTAMPTZ_TBL WHERE d1 BETWEEN '1902-01-01' AND '2038-01-01';
 
-SELECT date_trunc( 'week', timestamp with time zone '2004-02-29 15:44:17.71393' ) AS week_trunc;
-
+SELECT date_trunc('week', timestamp with time zone '2004-02-29 15:44:17.71393') AS week_trunc;
 SELECT date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'Australia/Sydney') as sydney_trunc;  -- zone name
 SELECT date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'GMT') as gmt_trunc;  -- fixed-offset abbreviation
 SELECT date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc;  -- variable-offset abbreviation
 
+SELECT date_trunc('7 day'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS week_trunc;
+SELECT date_trunc('3 month'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Australia/Sydney') as sydney_trunc;  -- zone name
+SELECT date_trunc('12 hour'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'GMT') as gmt_trunc;  -- fixed-offset abbreviation
+SELECT date_trunc('6 hour'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc;  -- variable-offset abbreviation
+SELECT date_trunc('6 minutes'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc;  -- variable-offset abbreviation
+SELECT date_trunc('10 second'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS tensec_trunc;
+SELECT date_trunc('500 msecond'::interval, timestamp with time zone '2004-02-29 15:44:17.71393') AS halfsec_trunc;
+
+-- errors
+SELECT date_trunc('1 month 7 day'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval1;
+SELECT date_trunc('1 month 01:00:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval2;
+SELECT date_trunc('1 day 00:30:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval3;
+SELECT date_trunc('7 month'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval4;
+SELECT date_trunc('3 day'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval5;
+SELECT date_trunc('00:23:00'::interval, timestamp with time zone '2001-02-16 20:38:40+00', 'Europe/Warsaw') AS bad_interval6;
+
 -- verify date_bin behaves the same as date_trunc for relevant intervals
 SELECT
   str,
   interval,
-  date_trunc(str, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal
+  date_trunc(str, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal_str,
+  date_trunc(interval::interval, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal_interval
 FROM (
   VALUES
   ('day', '1 d'),
@@ -478,6 +494,26 @@ SELECT * FROM generate_series('2021-12-31 23:00:00+00'::timestamptz,
                               '2020-12-31 23:00:00+00'::timestamptz,
                               '-1 month'::interval,
                               'Europe/Warsaw');
+SET TimeZone to 'Europe/Warsaw';
+-- DST - 23 hours in day
+SELECT ts,
+       date_trunc('1 hour'::interval, ts, 'Europe/Warsaw') AS one_hour_bin,
+       date_trunc('2 hour'::interval, ts, 'Europe/Warsaw') AS two_hours_bin,
+       date_trunc('3 hour'::interval, ts, 'Europe/Warsaw') AS three_hours_bin
+   FROM generate_series('2022-03-26 21:00:00+00'::timestamptz,
+                        '2022-03-27 07:00:00+00'::timestamptz,
+                        '30 min'::interval,
+                        'Europe/Warsaw') AS ts;
+-- DST - 25 hours in day
+SELECT ts,
+       date_trunc('1 hour'::interval, ts, 'Europe/Warsaw') AS one_hour_bin,
+       date_trunc('2 hour'::interval, ts, 'Europe/Warsaw') AS two_hours_bin,
+       date_trunc('3 hour'::interval, ts, 'Europe/Warsaw') AS three_hours_bin
+   FROM generate_series('2022-10-29 21:00:00+00'::timestamptz,
+                        '2022-10-30 07:00:00+00'::timestamptz,
+                        '30 min'::interval,
+                        'Europe/Warsaw') AS ts;
+
 RESET TimeZone;
 
 --