*** pgsql/src/backend/commands/conversioncmds.c	2008/01/01 19:45:48	1.32
--- pgsql/src/backend/commands/conversioncmds.c	2009/02/27 16:35:31	1.32.2.1
***************
*** 8,14 ****
   *
   *
   * IDENTIFICATION
!  *	  $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.31 2007/02/14 01:58:56 tgl Exp $
   *
   *-------------------------------------------------------------------------
   */
--- 8,14 ----
   *
   *
   * IDENTIFICATION
!  *	  $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.32 2008/01/01 19:45:48 momjian Exp $
   *
   *-------------------------------------------------------------------------
   */
*************** CreateConversionCommand(CreateConversion
*** 47,52 ****
--- 47,53 ----
  	const char *to_encoding_name = stmt->to_encoding_name;
  	List	   *func_name = stmt->func_name;
  	static Oid	funcargs[] = {INT4OID, INT4OID, CSTRINGOID, INTERNALOID, INT4OID};
+ 	char		result[1];
  
  	/* Convert list of names to a name and namespace */
  	namespaceId = QualifiedNameGetCreationNamespace(stmt->conversion_name,
*************** CreateConversionCommand(CreateConversion
*** 87,92 ****
--- 88,106 ----
  					   NameListToString(func_name));
  
  	/*
+ 	 * Check that the conversion function is suitable for the requested
+ 	 * source and target encodings. We do that by calling the function with
+ 	 * an empty string; the conversion function should throw an error if it
+ 	 * can't perform the requested conversion.
+ 	 */
+ 	OidFunctionCall5(funcoid,
+ 					 Int32GetDatum(from_encoding),
+ 					 Int32GetDatum(to_encoding),
+ 					 CStringGetDatum(""),
+ 					 CStringGetDatum(result),
+ 					 Int32GetDatum(0));
+ 
+ 	/*
  	 * All seem ok, go ahead (possible failure would be a duplicate conversion
  	 * name)
  	 */