diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 2e7a540f83..20d4987e0f 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -7639,6 +7639,15 @@ SELECT regexp_match('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
+
+
+ In to_timestamp and to_date,
+ negative years are treated as signifying BC. If you write both a
+ negative year and an explicit BC field, you get AD
+ again. An input of year zero is treated as 1 BC.
+
+
+
In to_timestamp and to_date,
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 75c85a3007..67271ba3cb 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -4570,8 +4570,11 @@ do_to_timestamp(text *date_txt, text *fmt, Oid collid, bool std,
{
/* If a 4-digit year is provided, we use that and ignore CC. */
tm->tm_year = tmfc.year;
- if (tmfc.bc && tm->tm_year > 0)
- tm->tm_year = -(tm->tm_year - 1);
+ if (tmfc.bc)
+ tm->tm_year = -tm->tm_year;
+ /* correct for our representation of BC years */
+ if (tm->tm_year < 0)
+ tm->tm_year++;
}
fmask |= DTK_M(YEAR);
}
diff --git a/src/test/regress/expected/horology.out b/src/test/regress/expected/horology.out
index c8c33a0fc0..7f82dcfbfe 100644
--- a/src/test/regress/expected/horology.out
+++ b/src/test/regress/expected/horology.out
@@ -2916,6 +2916,45 @@ SELECT to_date('2458872', 'J');
01-23-2020
(1 row)
+--
+-- Check handling of BC dates
+--
+SELECT to_date('44-02-01 BC','YYYY-MM-DD BC');
+ to_date
+---------------
+ 02-01-0044 BC
+(1 row)
+
+SELECT to_date('-44-02-01','YYYY-MM-DD');
+ to_date
+---------------
+ 02-01-0044 BC
+(1 row)
+
+SELECT to_date('-44-02-01 BC','YYYY-MM-DD BC');
+ to_date
+------------
+ 02-01-0044
+(1 row)
+
+SELECT to_timestamp('44-02-01 11:12:13 BC','YYYY-MM-DD HH24:MI:SS BC');
+ to_timestamp
+---------------------------------
+ Fri Feb 01 11:12:13 0044 PST BC
+(1 row)
+
+SELECT to_timestamp('-44-02-01 11:12:13','YYYY-MM-DD HH24:MI:SS');
+ to_timestamp
+---------------------------------
+ Fri Feb 01 11:12:13 0044 PST BC
+(1 row)
+
+SELECT to_timestamp('-44-02-01 11:12:13 BC','YYYY-MM-DD HH24:MI:SS BC');
+ to_timestamp
+------------------------------
+ Mon Feb 01 11:12:13 0044 PST
+(1 row)
+
--
-- Check handling of multiple spaces in format and/or input
--
@@ -3183,6 +3222,12 @@ SELECT to_date('2016 366', 'YYYY DDD'); -- ok
SELECT to_date('2016 367', 'YYYY DDD');
ERROR: date/time field value out of range: "2016 367"
+SELECT to_date('0000-02-01','YYYY-MM-DD'); -- allowed, though it shouldn't be
+ to_date
+---------------
+ 02-01-0001 BC
+(1 row)
+
--
-- Check behavior with SQL-style fixed-GMT-offset time zone (cf bug #8572)
--
diff --git a/src/test/regress/sql/horology.sql b/src/test/regress/sql/horology.sql
index c464e6766c..fed21a53c8 100644
--- a/src/test/regress/sql/horology.sql
+++ b/src/test/regress/sql/horology.sql
@@ -426,6 +426,17 @@ SELECT to_date('1 4 1902', 'Q MM YYYY'); -- Q is ignored
SELECT to_date('3 4 21 01', 'W MM CC YY');
SELECT to_date('2458872', 'J');
+--
+-- Check handling of BC dates
+--
+
+SELECT to_date('44-02-01 BC','YYYY-MM-DD BC');
+SELECT to_date('-44-02-01','YYYY-MM-DD');
+SELECT to_date('-44-02-01 BC','YYYY-MM-DD BC');
+SELECT to_timestamp('44-02-01 11:12:13 BC','YYYY-MM-DD HH24:MI:SS BC');
+SELECT to_timestamp('-44-02-01 11:12:13','YYYY-MM-DD HH24:MI:SS');
+SELECT to_timestamp('-44-02-01 11:12:13 BC','YYYY-MM-DD HH24:MI:SS BC');
+
--
-- Check handling of multiple spaces in format and/or input
--
@@ -511,6 +522,7 @@ SELECT to_date('2015 366', 'YYYY DDD');
SELECT to_date('2016 365', 'YYYY DDD'); -- ok
SELECT to_date('2016 366', 'YYYY DDD'); -- ok
SELECT to_date('2016 367', 'YYYY DDD');
+SELECT to_date('0000-02-01','YYYY-MM-DD'); -- allowed, though it shouldn't be
--
-- Check behavior with SQL-style fixed-GMT-offset time zone (cf bug #8572)