Add two new format fields for use with to_char(), to_date() and

to_timestamp():
    - ID for day-of-week
    - IDDD for day-of-year

This makes it possible to convert ISO week dates to and from text
fully represented in either week ('IYYY-IW-ID') or day-of-year
('IYYY-IDDD') format.

I have also added an 'isoyear' field for use with extract / date_part.

Brendan Jurd

doc/src/sgml/func.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.358 2007/02/14 18:46:08 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.359 2007/02/16 03:39:44 momjian Exp $ -->
 
  <chapter id="functions">
   <title>Functions and Operators</title>
@@ -4539,7 +4539,7 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
        </row>
        <row>
         <entry><literal>I</literal></entry>
-        <entry>last digits of ISO year</entry>
+        <entry>last digit of ISO year</entry>
        </row>
        <row>
         <entry><literal>BC</literal> or <literal>B.C.</literal> or
@@ -4607,6 +4607,10 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
         <entry><literal>DDD</literal></entry>
         <entry>day of year (001-366)</entry>
        </row>
+       <row>
+        <entry><literal>IDDD</literal></entry>
+        <entry>ISO day of year (001-371; day 1 of the year is Monday of the first ISO week.)</entry>
+       </row>
        <row>
         <entry><literal>DD</literal></entry>
         <entry>day of month (01-31)</entry>
@@ -4615,6 +4619,10 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
         <entry><literal>D</literal></entry>
         <entry>day of week (1-7; Sunday is 1)</entry>
        </row>
+       <row>
+        <entry><literal>ID</literal></entry>
+        <entry>ISO day of week (1-7; Monday is 1)</entry>
+       </row>
        <row>
         <entry><literal>W</literal></entry>
         <entry>week of month (1-5) (The first week starts on the first day of the month.)</entry>
@@ -4625,7 +4633,7 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
        </row>
        <row>
         <entry><literal>IW</literal></entry>
-        <entry>ISO week number of year (The first Thursday of the new year is in week 1.)</entry>
+        <entry>ISO week number of year (1 - 53; the first Thursday of the new year is in week 1.)</entry>
        </row>
        <row>
         <entry><literal>CC</literal></entry>
@@ -4791,6 +4799,27 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
       </para>
      </listitem>
 
+     <listitem>
+      <para>
+       An ISO week date (as distinct from a Gregorian date) can be specified to <function>to_timestamp</function> and <function>to_date</function> in one of two ways:
+       <itemizedlist>
+        <listitem>
+	 <para>
+	  Year, week and weekday, for example <literal>to_date('2006-42-4', 'IYYY-IW-ID')</literal> returns the date <literal>2006-10-19</literal>.  If you omit the weekday it is assumed to be 1 (Monday).
+	 </para>
+	</listitem>
+	<listitem>
+	 <para>
+	  Year and day of year, for example <literal>to_date('2006-291', 'IYYY-IDDD')</literal> also returns <literal>2006-10-19</literal>.
+	 </para>
+	</listitem>
+       </itemizedlist>
+      </para>
+      <para>
+       Attempting to construct a date using a mixture of ISO week and Gregorian date fields is nonsensical, and could yield unexpected results.  In the context of an ISO year, the concept of a 'month' or 'day of month' has no meaning.  In the context of a Gregorian year, the ISO week has no meaning.  Users should take care to keep Gregorian and ISO date specifications separate.
+      </para>
+     </listitem>
+
      <listitem>
       <para>
        Millisecond (<literal>MS</literal>) and microsecond (<literal>US</literal>)
@@ -5776,6 +5805,29 @@ SELECT EXTRACT(HOUR FROM TIMESTAMP '2001-02-16 20:38:40');
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><literal>isoyear</literal></term>
+      <listitem>
+       <para>
+        The <acronym>ISO</acronym> 8601 year that the date falls in (not applicable to intervals).
+       </para>
+
+<screen>
+SELECT EXTRACT(ISOYEAR FROM DATE '2006-01-01');
+<lineannotation>Result: </lineannotation><computeroutput>2005</computeroutput>
+SELECT EXTRACT(ISOYEAR FROM DATE '2006-01-02');
+<lineannotation>Result: </lineannotation><computeroutput>2006</computeroutput>
+</screen>
+
+       <para>
+        Each <acronym>ISO</acronym> year begins with the Monday of the week containing the 4th of January, so in early January or late December the <acronym>ISO</acronym> year may be different from the Gregorian year.  See the <literal>week</literal> field for more information.
+       </para>
+       <para>
+        This field is not available in PostgreSQL releases prior to 8.3.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><literal>microseconds</literal></term>
       <listitem>

src/backend/utils/adt/date.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.127 2007/01/05 22:19:40 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.128 2007/02/16 03:39:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1748,6 +1748,7 @@ time_part(PG_FUNCTION_ARGS)
 			case DTK_DECADE:
 			case DTK_CENTURY:
 			case DTK_MILLENNIUM:
+			case DTK_ISOYEAR:
 			default:
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),

src/backend/utils/adt/datetime.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.175 2007/01/05 22:19:40 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.176 2007/02/16 03:39:45 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -125,6 +125,7 @@ static const datetkn datetktbl[] = {
 	{"h", UNITS, DTK_HOUR},		/* "hour" */
 	{LATE, RESERV, DTK_LATE},	/* "infinity" reserved for "late time" */
 	{INVALID, RESERV, DTK_INVALID},		/* "invalid" reserved for bad time */
+	{"isoyear", UNITS, DTK_ISOYEAR},	/* year in terms of the ISO week date */
 	{"j", UNITS, DTK_JULIAN},
 	{"jan", MONTH, 1},
 	{"january", MONTH, 1},

src/backend/utils/adt/formatting.c

 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.124 2007/02/14 05:10:55 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.125 2007/02/16 03:39:45 momjian Exp $
  *
  *
  *	 Portions Copyright (c) 1999-2007, PostgreSQL Global Development Group
@@ -379,6 +379,7 @@ typedef struct
 				ddd,
 				mm,
 				ms,
+				iyear,
 				year,
 				bc,
 				iw,
@@ -528,7 +529,7 @@ static KeySuffix DCH_suff[] = {
  * position or -1 if char is not used in the KeyWord. Search example for
  * string "MM":
  *	1)	see in index to index['M' - 32],
- *	2)	take keywords position (enum DCH_MM) from index
+ *	2)	take keywords position (enum DCH_MI) from index
  *	3)	run sequential search in keywords[] from this position
  *
  * ----------
@@ -554,6 +555,8 @@ typedef enum
 	DCH_HH24,
 	DCH_HH12,
 	DCH_HH,
+	DCH_IDDD,
+	DCH_ID,
 	DCH_IW,
 	DCH_IYYY,
 	DCH_IYY,
@@ -598,6 +601,8 @@ typedef enum
 	DCH_hh24,
 	DCH_hh12,
 	DCH_hh,
+	DCH_iddd,
+	DCH_id,
 	DCH_iw,
 	DCH_iyyy,
 	DCH_iyy,
@@ -696,13 +701,15 @@ static const KeyWord DCH_keywords[] = {
 	{"HH24", 4, dch_time, DCH_HH24, TRUE},		/* H */
 	{"HH12", 4, dch_time, DCH_HH12, TRUE},
 	{"HH", 2, dch_time, DCH_HH, TRUE},
-	{"IW", 2, dch_date, DCH_IW, TRUE},	/* I */
+	{"IDDD", 4, dch_date, DCH_IDDD, TRUE},	/* I */
+	{"ID", 2, dch_date, DCH_ID, TRUE},
+	{"IW", 2, dch_date, DCH_IW, TRUE},
 	{"IYYY", 4, dch_date, DCH_IYYY, TRUE},
 	{"IYY", 3, dch_date, DCH_IYY, TRUE},
 	{"IY", 2, dch_date, DCH_IY, TRUE},
 	{"I", 1, dch_date, DCH_I, TRUE},
 	{"J", 1, dch_date, DCH_J, TRUE},	/* J */
-	{"MI", 2, dch_time, DCH_MI, TRUE},
+	{"MI", 2, dch_time, DCH_MI, TRUE},	/* M */
 	{"MM", 2, dch_date, DCH_MM, TRUE},
 	{"MONTH", 5, dch_date, DCH_MONTH, FALSE},
 	{"MON", 3, dch_date, DCH_MON, FALSE},
@@ -740,7 +747,9 @@ static const KeyWord DCH_keywords[] = {
 	{"hh24", 4, dch_time, DCH_HH24, TRUE},		/* h */
 	{"hh12", 4, dch_time, DCH_HH12, TRUE},
 	{"hh", 2, dch_time, DCH_HH, TRUE},
-	{"iw", 2, dch_date, DCH_IW, TRUE},	/* i */
+	{"iddd", 4, dch_date, DCH_IDDD, TRUE},	/* i */
+	{"id", 2, dch_date, DCH_ID, TRUE},
+	{"iw", 2, dch_date, DCH_IW, TRUE},
 	{"iyyy", 4, dch_date, DCH_IYYY, TRUE},
 	{"iyy", 3, dch_date, DCH_IYY, TRUE},
 	{"iy", 2, dch_date, DCH_IY, TRUE},
@@ -830,10 +839,10 @@ static const int DCH_index[KeyWord_INDEX_SIZE] = {
 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 	-1, -1, -1, -1, -1, DCH_A_D, DCH_B_C, DCH_CC, DCH_DAY, -1,
-	DCH_FX, -1, DCH_HH24, DCH_IW, DCH_J, -1, -1, DCH_MI, -1, -1,
+	DCH_FX, -1, DCH_HH24, DCH_IDDD, DCH_J, -1, -1, DCH_MI, -1, -1,
 	DCH_P_M, DCH_Q, DCH_RM, DCH_SSSS, DCH_TZ, DCH_US, -1, DCH_WW, -1, DCH_Y_YYY,
 	-1, -1, -1, -1, -1, -1, -1, DCH_a_d, DCH_b_c, DCH_cc,
-	DCH_day, -1, DCH_fx, -1, DCH_hh24, DCH_iw, DCH_j, -1, -1, DCH_mi,
+	DCH_day, -1, DCH_fx, -1, DCH_hh24, DCH_iddd, DCH_j, -1, -1, DCH_mi,
 	-1, -1, DCH_p_m, DCH_q, DCH_rm, DCH_ssss, DCH_tz, DCH_us, -1, DCH_ww,
 	-1, DCH_y_yyy, -1, -1, -1, -1
 
@@ -2429,9 +2438,13 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			return strlen(p_inout);
 
 		case DCH_DDD:
+		case DCH_IDDD:
 			if (is_to_char)
 			{
-				sprintf(inout, "%0*d", S_FM(suf) ? 0 : 3, tm->tm_yday);
+				sprintf(inout, "%0*d", S_FM(suf) ? 0 : 3, 
+					(arg == DCH_DDD) ? 
+					tm->tm_yday :
+					date2isoyearday(tm->tm_year, tm->tm_mon, tm->tm_mday));
 				if (S_THth(suf))
 					str_numth(p_inout, inout, S_TH_TYPE(suf));
 				return strlen(p_inout);
@@ -2473,10 +2486,14 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			break;
 		case DCH_D:
+		case DCH_ID:
 			INVALID_FOR_INTERVAL;
 			if (is_to_char)
 			{
+				if (arg == DCH_D)
 					sprintf(inout, "%d", tm->tm_wday + 1);
+				else
+					sprintf(inout, "%d", (tm->tm_wday == 0) ? 7 : tm->tm_wday);
 				if (S_THth(suf))
 					str_numth(p_inout, inout, S_TH_TYPE(suf));
 				return strlen(p_inout);
@@ -2484,6 +2501,7 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			else
 			{
 				sscanf(inout, "%1d", &tmfc->d);
+				if (arg == DCH_D)
 					tmfc->d--;
 				return strspace_len(inout) + 1 + SKIP_THth(suf);
 			}
@@ -2625,15 +2643,18 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			else
 			{
+				int *field;
+				field = (arg == DCH_YYYY) ? &tmfc->year : &tmfc->iyear;
+
 				if (S_FM(suf) || is_next_separator(node))
 				{
-					sscanf(inout, "%d", &tmfc->year);
+					sscanf(inout, "%d", field);
 					tmfc->yysz = 4;
 					return strdigits_len(inout) + SKIP_THth(suf);
 				}
 				else
 				{
-					sscanf(inout, "%04d", &tmfc->year);
+					sscanf(inout, "%04d", field);
 					tmfc->yysz = 4;
 					return strspace_len(inout) + 4 + SKIP_THth(suf);
 				}
@@ -2657,16 +2678,19 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			else
 			{
-				sscanf(inout, "%03d", &tmfc->year);
+				int *field;
+				field = (arg == DCH_YYY) ? &tmfc->year : &tmfc->iyear;
+
+				sscanf(inout, "%03d", field);
 
 				/*
 				 * 3-digit year: '100' ... '999' = 1100 ... 1999 '000' ...
 				 * '099' = 2000 ... 2099
 				 */
-				if (tmfc->year >= 100)
-					tmfc->year += 1000;
+				if (*field >= 100)
+					*field += 1000;
 				else
-					tmfc->year += 2000;
+					*field += 2000;
 				tmfc->yysz = 3;
 				return strspace_len(inout) + 3 + SKIP_THth(suf);
 			}
@@ -2689,16 +2713,19 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			else
 			{
-				sscanf(inout, "%02d", &tmfc->year);
+				int *field;
+				field = (arg == DCH_YY) ? &tmfc->year : &tmfc->iyear;
+
+				sscanf(inout, "%02d", field);
 
 				/*
 				 * 2-digit year: '00' ... '69'	= 2000 ... 2069 '70' ... '99'
 				 * = 1970 ... 1999
 				 */
-				if (tmfc->year < 70)
-					tmfc->year += 2000;
+				if (*field < 70)
+					*field += 2000;
 				else
-					tmfc->year += 1900;
+					*field += 1900;
 				tmfc->yysz = 2;
 				return strspace_len(inout) + 2 + SKIP_THth(suf);
 			}
@@ -2721,12 +2748,15 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			else
 			{
-				sscanf(inout, "%1d", &tmfc->year);
+				int *field;
+				field = (arg == DCH_Y) ? &tmfc->year : &tmfc->iyear;
+
+				sscanf(inout, "%1d", field);
 
 				/*
 				 * 1-digit year: always +2000
 				 */
-				tmfc->year += 2000;
+				*field += 2000;
 				tmfc->yysz = 1;
 				return strspace_len(inout) + 1 + SKIP_THth(suf);
 			}
@@ -3297,7 +3327,8 @@ do_to_timestamp(text *date_txt, text *fmt,
 {
 	FormatNode *format;
 	TmFromChar	tmfc;
-	int			fmt_len;
+	int			fmt_len,
+				year;
 
 	ZERO_tm(tm);
 	*fsec = 0;
@@ -3447,7 +3478,13 @@ do_to_timestamp(text *date_txt, text *fmt,
 			break;
 	}
 
-	if (tmfc.year)
+	/*
+	 * Only one year value is used.  If iyear (the ISO year) is defined, it takes precedence.  
+	 * Otherwise year (the Gregorian year) is used.
+	 */
+	year = (tmfc.iyear) ? tmfc.iyear : tmfc.year;
+
+	if (year)
 	{
 		/*
 		 * If CC and YY (or Y) are provided, use YY as 2 low-order digits
@@ -3458,14 +3495,14 @@ do_to_timestamp(text *date_txt, text *fmt,
 		 */
 		if (tmfc.cc && tmfc.yysz <= 2)
 		{
-			tm->tm_year = tmfc.year % 100;
+			tm->tm_year = year % 100;
 			if (tm->tm_year)
 				tm->tm_year += (tmfc.cc - 1) * 100;
 			else
 				tm->tm_year = tmfc.cc * 100;
 		}
 		else
-			tm->tm_year = tmfc.year;
+			tm->tm_year = year;
 	}
 	else if (tmfc.cc)			/* use first year of century */
 		tm->tm_year = (tmfc.cc - 1) * 100 + 1;
@@ -3485,23 +3522,52 @@ do_to_timestamp(text *date_txt, text *fmt,
 		j2date(tmfc.j, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
 
 	if (tmfc.iw)
+	{
+		/* 
+		 * Since the user has employed the IW field, it is assumed that the value in tmfc.d 
+		 * is in ISO day-of-week form (1 = Monday), as set by the ID field.  Mixing IW and D 
+		 * will yield weird results.
+		 *
+		 * tmfc.iyear must have been set (e.g., with IYYY) for this to work properly (an ISO week
+		 * without an ISO year is meaningless).
+		 *
+		 * If tmfc.d is not set, then the date is left at the beginning of the ISO week (Monday).
+		 */
+		if (tmfc.d)
+		{
+			isoweekdate2date(tmfc.iw, tmfc.d, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
+		}
+		else
 			isoweek2date(tmfc.iw, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
+	}
+
 
 	if (tmfc.d)
 		tm->tm_wday = tmfc.d;
 	if (tmfc.dd)
 		tm->tm_mday = tmfc.dd;
-	if (tmfc.ddd)
+	if (tmfc.ddd && !tmfc.iyear)
 		tm->tm_yday = tmfc.ddd;
 	if (tmfc.mm)
 		tm->tm_mon = tmfc.mm;
 
+	if (tmfc.ddd && (tm->tm_mon <= 1 || tm->tm_mday <= 1))
+	{
 		/*
-	 * we don't ignore DDD
+		 * If the iyear field is set, the value of ddd is taken to be an ISO day-of-year.
+		 * Otherwise, it is a Gregorian day-of-year.
+		 * Either way, since the month and day fields have not been set by some other means,
+		 * the value of ddd will be used to compute them.
 		 */
-	if (tmfc.ddd && (tm->tm_mon <= 1 || tm->tm_mday <= 1))
+		if (tmfc.iyear)
+		{
+			int j0;		// zeroth day of the ISO year, in Julian
+			j0 = isoweek2j(tmfc.iyear, 1) - 1;
+
+			j2date(j0 + tmfc.ddd, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
+		}
+		else
 		{
-		/* count mday and mon from yday */
 			int		   *y,
 						i;
 
@@ -3528,6 +3594,7 @@ do_to_timestamp(text *date_txt, text *fmt,
 				tm->tm_mday = i == 0 ? tm->tm_yday :
 					tm->tm_yday - y[i - 1];
 		}
+	}
 
 #ifdef HAVE_INT64_TIMESTAMP
 	if (tmfc.ms)

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.171 2007/01/05 22:19:42 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.172 2007/02/16 03:39:45 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3749,32 +3749,57 @@ interval_trunc(PG_FUNCTION_ARGS)
 	PG_RETURN_INTERVAL_P(result);
 }
 
-/* isoweek2date()
- * Convert ISO week of year number to date.
- * The year field must be specified with the ISO year!
- * karel 2000/08/07
+/* isoweek2j()
+ *
+ * 	Return the Julian day which corresponds to the first day (Monday) of the given ISO 8601 year and week.
+ * 	Julian days are used to convert between ISO week dates and Gregorian dates.
  */
-void
-isoweek2date(int woy, int *year, int *mon, int *mday)
+int
+isoweek2j(int year, int week)
 {
 	int			day0,
-				day4,
-				dayn;
+				day4;
 
-	if (!*year)
+	if (!year)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 		   errmsg("cannot calculate week number without year information")));
 
 	/* fourth day of current year */
-	day4 = date2j(*year, 1, 4);
+	day4 = date2j(year, 1, 4);
 
 	/* day0 == offset to first day of week (Monday) */
 	day0 = j2day(day4 - 1);
 
-	dayn = ((woy - 1) * 7) + (day4 - day0);
+	return ((week - 1) * 7) + (day4 - day0);
+}
+
+/* isoweek2date()
+ * Convert ISO week of year number to date.
+ * The year field must be specified with the ISO year!
+ * karel 2000/08/07
+ */
+void
+isoweek2date(int woy, int *year, int *mon, int *mday)
+{
+	j2date(isoweek2j(*year, woy), year, mon, mday);
+}
+
+/* isoweekdate2date()
+ *
+ * 	Convert an ISO 8601 week date (ISO year, ISO week and day of week) into a Gregorian date.
+ * 	Populates year, mon, and mday with the correct Gregorian values.
+ * 	year must be passed in as the ISO year.
+ */
+void
+isoweekdate2date(int isoweek, int isowday, int *year, int *mon, int *mday)
+{
+	int jday;
+
+	jday = isoweek2j(*year, isoweek);
+	jday += isowday - 1;
 
-	j2date(dayn, year, mon, mday);
+	j2date(jday, year, mon, mday);
 }
 
 /* date2isoweek()
@@ -3887,6 +3912,17 @@ date2isoyear(int year, int mon, int mday)
 }
 
 
+/* date2isoyearday()
+ *
+ * 	Returns the ISO 8601 day-of-year, given a Gregorian year, month and day.
+ * 	Possible return values are 1 through 371 (364 in non-leap years).
+ */
+int
+date2isoyearday(int year, int mon, int mday)
+{
+	return date2j(year, mon, mday) - isoweek2j(date2isoyear(year, mon, mday), 1) + 1;
+}
+
 /* timestamp_part()
  * Extract specified field from timestamp.
  */
@@ -4029,6 +4065,10 @@ timestamp_part(PG_FUNCTION_ARGS)
 #endif
 				break;
 
+			case DTK_ISOYEAR:
+				result = date2isoyear(tm->tm_year, tm->tm_mon, tm->tm_mday);
+				break;
+
 			case DTK_TZ:
 			case DTK_TZ_MINUTE:
 			case DTK_TZ_HOUR:
@@ -4256,6 +4296,10 @@ timestamptz_part(PG_FUNCTION_ARGS)
 #endif
 				break;
 
+			case DTK_ISOYEAR:
+				result = date2isoyear(tm->tm_year, tm->tm_mon, tm->tm_mday);
+				break;
+
 			default:
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

src/include/utils/datetime.h

@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/datetime.h,v 1.63 2007/01/05 22:19:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/datetime.h,v 1.64 2007/02/16 03:39:45 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -165,6 +165,7 @@
 #define DTK_DOY			33
 #define DTK_TZ_HOUR		34
 #define DTK_TZ_MINUTE	35
+#define DTK_ISOYEAR		36
 
 
 /*

src/include/utils/timestamp.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/timestamp.h,v 1.66 2007/01/05 22:19:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/timestamp.h,v 1.67 2007/02/16 03:39:45 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -331,8 +331,11 @@ extern int	timestamp_cmp_internal(Timestamp dt1, Timestamp dt2);
 /* timestamp comparison works for timestamptz also */
 #define timestamptz_cmp_internal(dt1,dt2)	timestamp_cmp_internal(dt1, dt2)
 
+extern int	isoweek2j(int year, int week);
 extern void	isoweek2date(int woy, int *year, int *mon, int *mday);
+extern void	isoweekdate2date(int isoweek, int isowday, int *year, int *mon, int *mday);
 extern int	date2isoweek(int year, int mon, int mday);
 extern int	date2isoyear(int year, int mon, int mday);
+extern int	date2isoyearday(int year, int mon, int mday);
 
 #endif   /* TIMESTAMP_H */

src/interfaces/ecpg/pgtypeslib/dt.h

-/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt.h,v 1.34 2006/03/11 04:38:39 momjian Exp $ */
+/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt.h,v 1.35 2007/02/16 03:39:45 momjian Exp $ */
 
 #ifndef DT_H
 #define DT_H
@@ -157,6 +157,7 @@ typedef double fsec_t;
 #define DTK_DOY			33
 #define DTK_TZ_HOUR		34
 #define DTK_TZ_MINUTE	35
+#define DTK_ISOYEAR		36
 
 
 /*

src/test/regress/sql/timestamp.sql

@@ -171,6 +171,11 @@ SELECT '' AS "54", d1 as "timestamp",
    date_part( 'usec', d1) AS usec
    FROM TIMESTAMP_TBL WHERE d1 BETWEEN '1902-01-01' AND '2038-01-01';
 
+SELECT '' AS "54", d1 as "timestamp",
+   date_part( 'isoyear', d1) AS isoyear, date_part( 'week', d1) AS week,
+   date_part( 'dow', d1) AS dow
+   FROM TIMESTAMP_TBL WHERE d1 BETWEEN '1902-01-01' AND '2038-01-01';
+
 -- TO_CHAR()
 SELECT '' AS to_char_1, to_char(d1, 'DAY Day day DY Dy dy MONTH Month month RM MON Mon mon') 
    FROM TIMESTAMP_TBL;
@@ -199,6 +204,12 @@ SELECT '' AS to_char_8, to_char(d1, 'YYYYTH YYYYth Jth')
 SELECT '' AS to_char_9, to_char(d1, 'YYYY A.D. YYYY a.d. YYYY bc HH:MI:SS P.M. HH:MI:SS p.m. HH:MI:SS pm') 
    FROM TIMESTAMP_TBL;   
 
+SELECT '' AS to_char_10, to_char(d1, 'IYYY IYY IY I IW IDDD ID')
+   FROM TIMESTAMP_TBL;
+
+SELECT '' AS to_char_11, to_char(d1, 'FMIYYY FMIYY FMIY FMI FMIW FMIDDD FMID')
+   FROM TIMESTAMP_TBL;
+
 -- TO_TIMESTAMP()
 SELECT '' AS to_timestamp_1, to_timestamp('0097/Feb/16 --> 08:14:30', 'YYYY/Mon/DD --> HH:MI:SS');
 
@@ -230,4 +241,18 @@ SELECT '' AS to_timestamp_13, to_timestamp('95-1116', 'YY-MMDD');
 
 SELECT '' AS to_timestamp_14, to_timestamp('995-1116', 'YYY-MMDD');
 
+SELECT '' AS to_timestamp_15, to_timestamp('2005426', 'YYYYWWD');
+
+SELECT '' AS to_timestamp_16, to_timestamp('2005300', 'YYYYDDD');
+
+SELECT '' AS to_timestamp_17, to_timestamp('2005527', 'IYYYIWID');
+
+SELECT '' AS to_timestamp_18, to_timestamp('005527', 'IYYIWID');
+
+SELECT '' AS to_timestamp_19, to_timestamp('05527', 'IYIWID');
+
+SELECT '' AS to_timestamp_20, to_timestamp('5527', 'IIWID');
+
+SELECT '' AS to_timestamp_21, to_timestamp('2005364', 'IYYYIDDD');
+
 SET DateStyle TO DEFAULT;

src/test/regress/sql/timestamptz.sql

@@ -169,6 +169,11 @@ SELECT '' AS "54", d1 as timestamptz,
    date_part( 'usec', d1) AS usec
    FROM TIMESTAMPTZ_TBL WHERE d1 BETWEEN '1902-01-01' AND '2038-01-01';
 
+SELECT '' AS "54", d1 as "timestamp",
+   date_part( 'isoyear', d1) AS isoyear, date_part( 'week', d1) AS week,
+   date_part( 'dow', d1) AS dow
+   FROM TIMESTAMP_TBL WHERE d1 BETWEEN '1902-01-01' AND '2038-01-01';
+
 -- TO_CHAR()
 SELECT '' AS to_char_1, to_char(d1, 'DAY Day day DY Dy dy MONTH Month month RM MON Mon mon') 
    FROM TIMESTAMPTZ_TBL;
@@ -197,8 +202,11 @@ SELECT '' AS to_char_8, to_char(d1, 'YYYYTH YYYYth Jth')
 SELECT '' AS to_char_9, to_char(d1, 'YYYY A.D. YYYY a.d. YYYY bc HH:MI:SS P.M. HH:MI:SS p.m. HH:MI:SS pm') 
    FROM TIMESTAMPTZ_TBL;   
 
-SELECT '' AS to_char_10, to_char(d1, 'YYYY WW IYYY IYY IY I IW') 
-   FROM TIMESTAMPTZ_TBL;
+SELECT '' AS to_char_10, to_char(d1, 'IYYY IYY IY I IW IDDD ID')
+   FROM TIMESTAMP_TBL;
+
+SELECT '' AS to_char_11, to_char(d1, 'FMIYYY FMIYY FMIY FMI FMIW FMIDDD FMID')
+   FROM TIMESTAMP_TBL;
 
 -- TO_TIMESTAMP()
 SELECT '' AS to_timestamp_1, to_timestamp('0097/Feb/16 --> 08:14:30', 'YYYY/Mon/DD --> HH:MI:SS');
@@ -231,9 +239,18 @@ SELECT '' AS to_timestamp_13, to_timestamp('95-1116', 'YY-MMDD');
 
 SELECT '' AS to_timestamp_14, to_timestamp('995-1116', 'YYY-MMDD');
 
-SELECT '' AS to_timestamp_15, to_timestamp('200401', 'IYYYIW');
+SELECT '' AS to_timestamp_15, to_timestamp('2005426', 'YYYYWWD');
+
+SELECT '' AS to_timestamp_16, to_timestamp('2005300', 'YYYYDDD');
+
+SELECT '' AS to_timestamp_17, to_timestamp('2005527', 'IYYYIWID');
+
+SELECT '' AS to_timestamp_18, to_timestamp('005527', 'IYYIWID');
+
+SELECT '' AS to_timestamp_19, to_timestamp('05527', 'IYIWID');
 
-SELECT '' AS to_timestamp_16, to_timestamp('200401', 'YYYYWW');
+SELECT '' AS to_timestamp_20, to_timestamp('5527', 'IIWID');
 
+SELECT '' AS to_timestamp_21, to_timestamp('2005364', 'IYYYIDDD');
 
 SET DateStyle TO DEFAULT;