Add note explaining that a mergejoinable equality operator is now

required if a datatype is to be accepted by GROUP BY, DISTINCT, or
ORDER BY.  This is documentation for code changes made pursuant to
pgsql-hackers discussion around 29-Nov-02.

diff --git a/doc/src/sgml/xoper.sgml b/doc/src/sgml/xoper.sgml
index 23db99705f743e5826abcaf2159a633378e1576f..395306bbd60e3234d1a257e97775f1466fac9352 100644 (file)
--- a/doc/src/sgml/xoper.sgml
+++ b/doc/src/sgml/xoper.sgml
@@ -1,5 +1,5 @@
 
 
  
@@ -472,6 +472,17 @@ table1.column1 OP table2.column2
      
     
 
+    
+    
+     GROUP BY and DISTINCT operations require each
+     datatype being grouped or compared to have a mergejoinable
+     equality operator named =.  The equality operator and its
+     associated SORT1 operator are used to implement these
+     operations.  Also, the associated SORT1 operator is the
+     default ordering operator for ORDER BY.
+    
+    
+
     
     
      In PostgreSQL versions before 7.3,