Apply (a somewhat revised version of) Greg Mullane's patch to eliminate

heuristic determination of day vs month in date/time input.  Add the
ability to specify that input is interpreted as yy-mm-dd order (which
formerly worked, but only for yy greater than 31).  DateStyle's input
component now has the preferred spellings DMY, MDY, or YMD; the older
keywords European and US are now aliases for the first two of these.
Per recent discussions on pgsql-general.

Author: tglsfdc

doc/src/sgml/datatype.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.120 2003/07/18 03:45:06 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.121 2003/07/29 00:03:17 tgl Exp $
 -->
 
  <chapter id="datatype">
@@ -1346,15 +1346,12 @@ SELECT b, char_length(b) FROM test2;
      Date and time input is accepted in almost any reasonable format, including
      ISO 8601, <acronym>SQL</acronym>-compatible, 
      traditional <productname>POSTGRES</productname>, and others.
-     For some formats, ordering of month and day in date input can be
+     For some formats, ordering of month, day, and year in date input is
      ambiguous and there is support for specifying the expected
-     ordering of these fields.
-     The command
-     <literal>SET datestyle TO 'US'</literal> 
-     or <literal>SET datestyle TO 'NonEuropean'</literal>
-     specifies the variant <quote>month before day</quote>, the command
-     <literal>SET datestyle TO 'European'</literal> sets the variant
-     <quote>day before month</quote>.
+     ordering of these fields.  Set the <varname>datestyle</> parameter
+     to <literal>MDY</> to select month-day-year interpretation,
+     <literal>DMY</> to select day-month-year interpretation, or
+     <literal>YMD</> to select year-month-day interpretation.
     </para>
 
     <para>
@@ -1410,36 +1407,42 @@ SELECT b, char_length(b) FROM test2;
        <tbody>
 	<row>
 	 <entry>January 8, 1999</entry>
-	 <entry>unambiguous</entry>
+	 <entry>unambiguous in any datestyle input mode</entry>
 	</row>
 	<row>
 	 <entry>1999-01-08</entry>
-	 <entry>ISO-8601 format, preferred</entry>
+	 <entry>ISO-8601, January 8 in any mode
+	 (recommended format)</entry>
 	</row>
 	<row>
 	 <entry>1/8/1999</entry>
-	 <entry>ambiguous (January 8 in U.S. mode; August 1 in European mode)</entry>
+	 <entry>January 8 in <literal>MDY</> mode;
+	  August 1 in <literal>DMY</> mode</entry>
 	</row>
 	<row>
 	 <entry>1/18/1999</entry>
-	 <entry>U.S. notation; January 18 in any mode</entry>
+	 <entry>January 18 in <literal>MDY</> mode;
+	  rejected in other modes</entry>
+	</row>
+	<row>
+	 <entry>01/02/03</entry>
+	 <entry>January 2, 2003 in <literal>MDY</> mode;
+	  February 1, 2003 in <literal>DMY</> mode;
+	  February 3, 2001 in <literal>YMD</> mode
+	 </entry>
 	</row>
 	<row>
 	 <entry>19990108</entry>
-	 <entry>ISO-8601; year, month, day</entry>
+	 <entry>ISO-8601; January 8, 1999 in any mode</entry>
 	</row>
 	<row>
 	 <entry>990108</entry>
-	 <entry>ISO-8601; year, month, day</entry>
+	 <entry>ISO-8601; January 8, 1999 in any mode</entry>
 	</row>
 	<row>
 	 <entry>1999.008</entry>
 	 <entry>year and day of year</entry>
 	</row>
-	<row>
-	 <entry>99008</entry>
-	 <entry>year and day of year</entry>
-	</row>
 	<row>
 	 <entry>J2451187</entry>
 	 <entry>Julian day</entry>
@@ -1480,7 +1483,8 @@ SELECT b, char_length(b) FROM test2;
      <para>
       Valid input for these types consists of a time of day followed
       by an optional time zone. (See <xref
-      linkend="datatype-datetime-time-table">.)  If a time zone is
+      linkend="datatype-datetime-time-table"> 
+      and <xref linkend="datatype-timezone-table">.)  If a time zone is
       specified in the input for <type>time without time zone</type>,
       it is silently ignored.
      </para>
@@ -1539,14 +1543,43 @@ SELECT b, char_length(b) FROM test2;
 	 <entry>040506-08</entry>
 	 <entry>ISO 8601</entry>
 	</row>
+	<row>
+	 <entry>04:05:06 PST</entry>
+	 <entry>timezone specified by name</entry>
+	</row>
        </tbody>
       </tgroup>
      </table>
 
-     <para>
-      Refer to <xref linkend="datatype-timezone-table"> for
-      more examples of time zones.
-     </para>
+      <table tocentry="1" id="datatype-timezone-table">
+       <title>Time Zone Input</title>
+       <tgroup cols="2">
+	<thead>
+	 <row>
+	  <entry>Example</entry>
+	  <entry>Description</entry>
+	 </row>
+	</thead>
+	<tbody>
+	 <row>
+	  <entry>PST</entry>
+	  <entry>Pacific Standard Time</entry>
+	 </row>
+	 <row>
+	  <entry>-8:00</entry>
+	  <entry>ISO-8601 offset for PST</entry>
+	 </row>
+	 <row>
+	  <entry>-800</entry>
+	  <entry>ISO-8601 offset for PST</entry>
+	 </row>
+	 <row>
+	  <entry>-8</entry>
+	  <entry>ISO-8601 offset for PST</entry>
+	 </row>
+	</tbody>
+       </tgroup>
+      </table>
     </sect3>
 
     <sect3>
@@ -1571,8 +1604,7 @@ SELECT b, char_length(b) FROM test2;
       Valid input for the time stamp types consists of a concatenation
       of a date and a time, followed by an optional
       <literal>AD</literal> or <literal>BC</literal>, followed by an
-      optional time zone. (See <xref
-      linkend="datatype-timezone-table">.)  Thus
+      optional time zone. Thus
 
 <programlisting>
 1999-01-08 04:05:06
@@ -1626,36 +1658,6 @@ January 8 04:05:06 1999 PST
       as <varname>timezone</> local time.  A different zone reference can
       be specified for the conversion using <literal>AT TIME ZONE</>.
      </para>
-
-      <table tocentry="1" id="datatype-timezone-table">
-       <title>Time Zone Input</title>
-       <tgroup cols="2">
-	<thead>
-	 <row>
-	  <entry>Example</entry>
-	  <entry>Description</entry>
-	 </row>
-	</thead>
-	<tbody>
-	 <row>
-	  <entry>PST</entry>
-	  <entry>Pacific Standard Time</entry>
-	 </row>
-	 <row>
-	  <entry>-8:00</entry>
-	  <entry>ISO-8601 offset for PST</entry>
-	 </row>
-	 <row>
-	  <entry>-800</entry>
-	  <entry>ISO-8601 offset for PST</entry>
-	 </row>
-	 <row>
-	  <entry>-8</entry>
-	  <entry>ISO-8601 offset for PST</entry>
-	 </row>
-	</tbody>
-       </tgroup>
-      </table>
     </sect3>
 
     <sect3>
@@ -1760,7 +1762,7 @@ January 8 04:05:06 1999 PST
 	 <row>
 	  <entry><literal>now</literal></entry>
           <entry><type>date</type>, <type>time</type>, <type>timestamp</type></entry>
-	  <entry>current transaction time</entry>
+	  <entry>current transaction's start time</entry>
 	 </row>
 	 <row>
 	  <entry><literal>today</literal></entry>
@@ -1805,9 +1807,10 @@ January 8 04:05:06 1999 PST
     </indexterm>
 
     <para>
-     The output format of the date/time types can be set to one of the four styles ISO 8601,
+     The output format of the date/time types can be set to one of the four
+     styles ISO 8601,
      <acronym>SQL</acronym> (Ingres), traditional POSTGRES, and
-     German, using the <literal>SET datestyle</literal>.  The default
+     German, using the command <literal>SET datestyle</literal>.  The default
      is the <acronym>ISO</acronym> format.  (The
      <acronym>SQL</acronym> standard requires the use of the ISO 8601
      format.  The name of the <quote>SQL</quote> output format is a
@@ -1854,9 +1857,10 @@ January 8 04:05:06 1999 PST
      </table>
 
     <para>
-     The <acronym>SQL</acronym> style has European and non-European
-     (U.S.) variants, which determines whether month follows day or
-     vice versa. (See <xref linkend="datatype-datetime-input">
+     In the <acronym>SQL</acronym> and POSTGRES styles, day appears before
+     month if DMY field ordering has been specified, otherwise month appears
+     before day.
+     (See <xref linkend="datatype-datetime-input">
      for how this setting also affects interpretation of input values.)
      <xref linkend="datatype-datetime-output2-table"> shows an
      example.
@@ -1867,22 +1871,27 @@ January 8 04:05:06 1999 PST
       <tgroup cols="3">
        <thead>
 	<row>
-	 <entry>Style Specification</entry>
-	 <entry>Description</entry>
-	 <entry>Example</entry>
+	 <entry>DateStyle setting</entry>
+	 <entry>Input Ordering</entry>
+	 <entry>Example Output</entry>
 	</row>
        </thead>
        <tbody>
 	<row>
-	 <entry>European</entry>
+	 <entry><literal>SQL, DMY</></entry>
 	 <entry><replaceable>day</replaceable>/<replaceable>month</replaceable>/<replaceable>year</replaceable></entry>
 	 <entry>17/12/1997 15:37:16.00 CET</entry>
 	</row>
 	<row>
-	 <entry>US</entry>
+	 <entry><literal>SQL, MDY</></entry>
 	 <entry><replaceable>month</replaceable>/<replaceable>day</replaceable>/<replaceable>year</replaceable></entry>
 	 <entry>12/17/1997 07:37:16.00 PST</entry>
 	</row>
+	<row>
+	 <entry><literal>Postgres, DMY</></entry>
+	 <entry><replaceable>day</replaceable>/<replaceable>month</replaceable>/<replaceable>year</replaceable></entry>
+	 <entry>Wed 17 Dec 07:37:16 1997 PST</entry>
+	</row>
        </tbody>
       </tgroup>
      </table>
@@ -1903,7 +1912,7 @@ January 8 04:05:06 1999 PST
      The date/time styles can be selected by the user using the
      <command>SET datestyle</command> command, the
      <varname>datestyle</varname> parameter in the
-     <filename>postgresql.conf</filename> configuration file, and the
+     <filename>postgresql.conf</filename> configuration file, or the
      <envar>PGDATESTYLE</envar> environment variable on the server or
      client.  The formatting function <function>to_char</function>
      (see <xref linkend="functions-formatting">) is also available as

doc/src/sgml/datetime.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.31 2003/04/07 01:29:25 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.32 2003/07/29 00:03:17 tgl Exp $
 -->
 
  <appendix id="datetime-appendix">
@@ -27,7 +27,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.31 2003/04/07 01:29:25 pe
    <title>Date/Time Input Interpretation</title>
 
    <para>
-    The date/time type inputs are all decoded using the following routine.
+    The date/time type inputs are all decoded using the following procedure.
    </para>
 
    <procedure>
@@ -103,78 +103,55 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.31 2003/04/07 01:29:25 pe
 
       <step>
        <para>
-	If not found, throw an error.
+	If still not found, throw an error.
        </para>
       </step>
      </substeps>
     </step>
 
     <step>
      <para>
-      The token is a number or number field.
+      When the token is a number or number field:
      </para>
 
      <substeps>
       <step>
        <para>
-	If there are more than 4 digits, 
+	If there are eight or six digits,
 	and if no other date fields have been previously read, then interpret 
-	as a <quote>concatenated date</quote> (e.g., <literal>19990118</literal>). 8
-	and 6 digits are interpreted as year, month, and day, while 7
-	and 5 digits are interpreted as year, day of year, respectively.
+	as a <quote>concatenated date</quote> (e.g.,
+	<literal>19990118</literal> or <literal>990118</literal>).
+	The interpretation is <literal>YYYYMMDD</> or <literal>YYMMDD</>.
        </para>
       </step>
 
       <step>
        <para>
 	If the token is three digits
-	and a year has already been decoded, then interpret as day of year.
+	and a year has already been read, then interpret as day of year.
        </para>
       </step>
 
       <step>
        <para>
 	If four or six digits and a year has already been read, then
-	interpret as a time.
+	interpret as a time (<literal>HHMM</> or <literal>HHMMSS</>).
        </para>
       </step>
 
       <step>
        <para>
-	If four or more digits, then interpret as a year.
+	If three or more digits and no date fields have yet been found,
+	interpret as a year (this forces yy-mm-dd ordering of the remaining
+	date fields).
        </para>
       </step>
 
       <step>
        <para>
-	If in European date mode, and if the day field has not yet been read,
-	and if the value is less than or equal to 31, then interpret as a day.
-       </para>
-      </step>
-
-      <step>
-       <para>
-	If the month field has not yet been read,
-	and if the value is less than or equal to 12, then interpret as a month.
-       </para>
-      </step>
-
-      <step>
-       <para>
-	If the day field has not yet been read,
-	and if the value is less than or equal to 31, then interpret as a day.
-       </para>
-      </step>
-
-      <step>
-       <para>
-	If two digits or four or more digits, then interpret as a year.
-       </para>
-      </step>
-
-      <step>
-       <para>
-	Otherwise, throw an error.
+        Otherwise the date field ordering is assumed to follow the
+	<varname>DateStyle</> setting: mm-dd-yy, dd-mm-yy, or yy-mm-dd.
+	Throw an error if a month or day field is found to be out of range.
        </para>
       </step>
      </substeps>

doc/src/sgml/func.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.160 2003/07/17 00:55:36 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.161 2003/07/29 00:03:17 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -6503,7 +6503,7 @@ SELECT current_setting('datestyle');
 
  current_setting
 -----------------
- ISO, US
+ ISO, MDY
 (1 row)
 </programlisting>
    </para>