Buffer to small ORA-22835 error after migration from 9i to 10g

Question

Hello Oracle-Experts,
I had to calculate hash-values for a corresponding clob-field which worked with oracle 9i (9.0.2.1)
After migration to oracle 10g (10.2.0.1.0) I get an ORA-22835 error (Buffer too small for CLOB to CHAR conversion.
Here is the output for the 10g version:     
     SQL*Plus: Release 10.2.0.1.0 - Production on Mi Jun 13 16:19:28 2007
     Copyright (c) 1982, 2005, Oracle. All rights reserved.
     Verbunden mit:
     Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
     With the Partitioning, OLAP and Data Mining options
     SQL> CREATE TABLE test_conv (value CLOB);
     Tabelle wurde erstellt. (Table created.)
     SQL> DECLARE vLong LONG:= LPAD('M',4400,'M');
     2 BEGIN
     3 INSERT INTO test_conv(value) VALUES (vLong);
     4 END;
     5 /
     PL/SQL-Prozedur erfolgreich abgeschlossen. (PL/SQL procedure successfully completed.)
     SQL> SELECT dbms_utility.get_hash_value(value,1,power(2,30)) from test_conv;
     SELECT dbms_utility.get_hash_value(value,1,power(2,30)) from test_conv
     FEHLER in Zeile 1:
     ORA-22835: Puffer zu klein für Konvertierung von CLOB zu CHAR oder BLOB zu RAW
     (tatsächlich: 4400, maximal: 4000)
     (Buffer too small for CLOB to CHAR or BLOB to RAW conversion (actual: 4400, maximum: 4000))
This is the result with     9i
     Verbunden mit:
     Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
     With the Partitioning, OLAP and Oracle Data Mining options
     JServer Release 9.2.0.1.0 - Production
     SQL> CREATE TABLE test_conv (value CLOB);
     Tabelle wurde angelegt.     (Table created.)
     SQL> DECLARE vLong LONG:= LPAD('M',4400,'M');
     2 BEGIN
     3 INSERT INTO test_conv(value) VALUES (vLong);
     4 END;
     5 /
     PL/SQL-Prozedur wurde erfolgreich abgeschlossen. (PL/SQL procedure successfully completed.)
     SQL> SELECT dbms_utility.get_hash_value(value,1,power(2,30)) from test_conv;
     DBMS_UTILITY.GET_HASH_VALUE(VALUE,1,POWER(2,30))
     478332438
Any help is appreciated.
Best Regards
Matthias

Answer 1

You have hit a bug, 3984527 - CLOB LARGER THAN 4000 INSERTED INTO VARCHAR2(4000) COLUMN IS.
You may want to check this metalink note: Note:388512.1 for further explanation and workarouds.
From the error message manual, Verbatim:
ORA-22835: Buffer too small for CLOB to CHAR or BLOB to RAW conversion (actual: string, maximum: string)
Cause: An attempt was made to convert CLOB to CHAR or BLOB to RAW, where the LOB size was bigger than the buffer limit for CHAR and RAW types. Note that widths are reported in characters if character length semantics are in effect for the column, otherwise widths are reported in bytes.
Action: Do one of the following:
1. Make the LOB smaller before performing the conversion, for example, by using SUBSTR on CLOB
2. Use DBMS_LOB.SUBSTR to convert CLOB to CHAR or BLOB to RAW.
~ Madrid.