Support use of function argument names to identify which actual arguments

match which function parameters.  The syntax uses AS, for example
	funcname(value AS arg1, anothervalue AS arg2)

Pavel Stehule

1 files changed, 19 insertions, 4 deletions

diff --git a/doc/src/sgml/ref/create_function.sgml b/doc/src/sgml/ref/create_function.sgml
index 0843a175638..6d7eb84d8f2 100644
--- a/doc/src/sgml/ref/create_function.sgml
+++ b/doc/src/sgml/ref/create_function.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.87 2009/10/02 18:13:04 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.88 2009/10/08 02:39:14 tgl Exp $
 -->
 
 <refentry id="SQL-CREATEFUNCTION">
@@ -65,7 +65,7 @@ CREATE [ OR REPLACE ] FUNCTION
    Also, <command>CREATE OR REPLACE FUNCTION</command> will not let
    you change the return type of an existing function.  To do that,
    you must drop and recreate the function.  (When using <literal>OUT</>
-   parameters, that means you cannot change the names or types of any
+   parameters, that means you cannot change the types of any
    <literal>OUT</> parameters except by dropping the function.)
   </para>
 
@@ -121,8 +121,11 @@ CREATE [ OR REPLACE ] FUNCTION
       <para>
        The name of an argument. Some languages (currently only PL/pgSQL) let
        you use the name in the function body.  For other languages the
-       name of an input argument is just extra documentation.  But the name
-       of an output argument is significant, since it defines the column
+       name of an input argument is just extra documentation, so far as
+       the function itself is concerned; but you can use input argument names
+       when calling a function to improve readability (see <xref
+       linkend="sql-syntax-calling-funcs">).  In any case, the name
+       of an output argument is significant, because it defines the column
        name in the result row type.  (If you omit the name for an output
        argument, the system will choose a default column name.)
       </para>
@@ -570,6 +573,18 @@ CREATE FUNCTION foo(int, int default 42) ...
     to replace it (this includes being a member of the owning role).
    </para>
 
+   <para>
+    When replacing an existing function with <command>CREATE OR REPLACE
+    FUNCTION</>, there are restrictions on changing parameter names.
+    You cannot change the name already assigned to any input parameter
+    (although you can add names to parameters that had none before).
+    If there is more than one output parameter, you cannot change the
+    names of the output parameters, because that would change the
+    column names of the anonymous composite type that describes the
+    function's result.  These restrictions are made to ensure that
+    existing calls of the function do not stop working when it is replaced.
+   </para>
+
  </refsect1>
 
  <refsect1 id="sql-createfunction-examples">