Fix date_trunct for December dates that are in the next year, e.g.:

        SELECT date_trunc('week', '2002-12-31'::date);

Backpatch to 8.0.X.

Per report from Nick Johnson.

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 632c97ef2fd03390183aab78bc9238a22eea586d..8b64711e63548e9493bc82b5ca59a916fab1513b 100644 (file)
--- 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 1.128 2005/06/30 03:48:58 neilc Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.129 2005/07/04 14:38:31 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2793,9 +2793,12 @@ timestamp_trunc(PG_FUNCTION_ARGS)
                /*
                 *  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 == 12)
+                   ++tm->tm_year;
                isoweek2date(woy, &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
                tm->tm_hour = 0;
                tm->tm_min = 0;
@@ -2924,9 +2927,12 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
                /*
                 *  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 == 12)
+                   ++tm->tm_year;
                isoweek2date(woy, &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
                tm->tm_hour = 0;
                tm->tm_min = 0;