Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.242
diff -c -c -r1.242 func.sgml
*** doc/src/sgml/func.sgml	25 Mar 2005 16:08:39 -0000	1.242
--- doc/src/sgml/func.sgml	30 Mar 2005 06:04:39 -0000
***************
*** 5472,5477 ****
--- 5472,5483 ----
          week starts on Monday.)  In other words, the first Thursday of
          a year is in week 1 of that year. (for <type>timestamp</type> values only)
         </para>
+        <para>
+         Because of this, it is possible for early January dates to be part of the 
+         52nd or 53rd week of the previous year.  For example, <literal>2005-01-01</>
+         is part of the 53rd week of year 2004, and <literal>2006-01-01</> is part of 
+         the 52nd week of year 2005.
+        </para>
  
  <screen>
  SELECT EXTRACT(WEEK FROM TIMESTAMP '2001-02-16 20:38:40');
Index: src/backend/utils/adt/timestamp.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v
retrieving revision 1.117
diff -c -c -r1.117 timestamp.c
*** src/backend/utils/adt/timestamp.c	31 Dec 2004 22:01:22 -0000	1.117
--- src/backend/utils/adt/timestamp.c	30 Mar 2005 06:04:41 -0000
***************
*** 2754,2765 ****
  		switch (val)
  		{
  			case DTK_WEEK:
! 				isoweek2date(date2isoweek(tm->tm_year, tm->tm_mon, tm->tm_mday), &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
  				tm->tm_hour = 0;
  				tm->tm_min = 0;
  				tm->tm_sec = 0;
  				fsec = 0;
  				break;
  			case DTK_MILLENNIUM:
  				/* see comments in timestamptz_trunc */
  				if (tm->tm_year > 0)
--- 2754,2776 ----
  		switch (val)
  		{
  			case DTK_WEEK:
! 			{
! 				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.
! 				 */
! 				if (woy >= 52 && tm->tm_mon == 1)
! 					--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;
  				break;
+ 			}
  			case DTK_MILLENNIUM:
  				/* see comments in timestamptz_trunc */
  				if (tm->tm_year > 0)
***************
*** 2874,2886 ****
  		switch (val)
  		{
  			case DTK_WEEK:
! 				isoweek2date(date2isoweek(tm->tm_year, tm->tm_mon, tm->tm_mday), &(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;
  				break;
  				/* one may consider DTK_THOUSAND and DTK_HUNDRED... */
  			case DTK_MILLENNIUM:
  
--- 2885,2908 ----
  		switch (val)
  		{
  			case DTK_WEEK:
! 			{
! 				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.
! 				 */
! 				if (woy >= 52 && tm->tm_mon == 1)
! 					--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;
  				break;
+ 			}
  				/* one may consider DTK_THOUSAND and DTK_HUNDRED... */
  			case DTK_MILLENNIUM:
  
***************
*** 3142,3148 ****
  	 * Sometimes the last few days in a year will fall into the first week
  	 * of the next year, so check for this.
  	 */
! 	if (result >= 53)
  	{
  		day4 = date2j(year + 1, 1, 4);
  
--- 3164,3170 ----
  	 * Sometimes the last few days in a year will fall into the first week
  	 * of the next year, so check for this.
  	 */
! 	if (result >= 52)
  	{
  		day4 = date2j(year + 1, 1, 4);
  
***************
*** 3198,3204 ****
  	 * Sometimes the last few days in a year will fall into the first week
  	 * of the next year, so check for this.
  	 */
! 	if (result >= 53)
  	{
  		day4 = date2j(year + 1, 1, 4);
  
--- 3220,3226 ----
  	 * Sometimes the last few days in a year will fall into the first week
  	 * of the next year, so check for this.
  	 */
! 	if (result >= 52)
  	{
  		day4 = date2j(year + 1, 1, 4);