ORA-12714 error using NVARCHAR2, REF CURSOR and TABLE FUNCTION

Question

Hello,
we have tested this simple script on all the following versions of Oracle: 9.2.0.3, 10.2.0.1.0 , 11.1.0.6.0 - but we got the same error in everyone of these.
CREATE OR REPLACE TYPE Rec_Prova IS OBJECT(
    Id INTEGER,
    NodeValue NVARCHAR2(50)
CREATE OR REPLACE TYPE Tab_Prova IS TABLE OF Rec_Prova;
DECLARE
    CurProva SYS_REFCURSOR;
    varTable Tab_Prova := Tab_Prova();
BEGIN
    OPEN CurProva FOR
        SELECT Id, NodeValue FROM TABLE(CAST(varTable AS Tab_Prova));
END;The error is: "ORA-12714: invalid national character set specified"
We know that changing the type of NodeValue from NVARCHAR2 to NCLOB it works, but the performances are very poor.
Therefore this solution is not acceptable for us.
We also know that if the character set of the database is set to unicode (NLS_NCHAR_CHARACTERSET = AL16UTF16) we can use the VARCHAR2 for store also the unicode characters and the problem is solved. But some of our customers can't change the settings of theirs databases... moreover, in this forum someone says:
"To all dba's who try to change the NLS_CHARACTERSET or NLS_NCHAR_CHARACTERSET by updating props$ . This is NOT supported and WILL corrupt your database. This is one of the best way's to destroy a complete dataset. Oracle Support will TRY to help you out of this but Oracle will NOT warrant that the data can be recoverd or recovered data is correct. Most likely you WILL be asked to do a FULL export and a COMPLETE rebuild of the database."
Is there any workaround except the two that I have mentioned?
Thank you in advance.
Edited by: user11929330 on 22-set-2009 7.50

Answer 1

ORA-12714: invalid national character set specified
Cause: Only UTF8 and AL16UTF16 are allowed to be used as the national character set
Action: Ensure that the specified national character set is valid
So it looks like that you should change the character set or go for NCLOB (and if you're on version 11, maybe securefiles gives you the performance you want).
-Andy