Fix wrong week returnded by date_trunc('week') for early dates in

January --- would return wrong year for 2005-01-01 and 2006-01-01.

per report from Robert Creager.

Backpatch to 8.0.X.

1 files changed, 7 insertions, 1 deletions

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 0403a609884..7a7923a908e 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.234.4.4 2005/03/25 16:08:49 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.234.4.5 2005/04/01 14:25:39 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -5460,6 +5460,12 @@ SELECT EXTRACT(SECOND FROM TIME '17:12:28.5');
         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');