Dg4odbc failure with MSSQL Driver

Question

Hi,
I know that this subject has been discussed many times but I couldn't find one that would have helped me.
My problem is the following :
I have a Oracle 11gR2 platform on RedHat 6 and I need to get data from a SQL Server 2005 / 2008.
To achieve this, I installed Microsoft driver for Linux and I'm using the dg4odbc with a Database Link.
All is fine until I need to retrieve data from SQL Server defined as varchar(max).
In this case, I can't solve the issue : [Microsoft][ODBC Driver 11 for SQL Server]String data, right truncation {01004}
If I connect using Microsoft tools (on the Red Hat box) like sqlcmd, I can execute the SQL queries without issue.
As soon as I try to get the same data through the Database link, I get the previous error.
As an example, I created on my SQL Server box a test table with the following definition and I inserted a record :
CREATE TABLE TEST ( col1 int, col2 varchar(30), col3 nvarchar(30), col4 varchar(max) )
INSERT INTO TEST VALUES ( 1, 'value2', N'value3', 'value4' )
I'm just doing a SELECT * FROM TEST@remote
Then, I activated the logs for dg4odbc and SQL Server driver.
Here is what I can see :
in the ODBC logs :
[ODBC][24984][1390400782.066544][SQLDescribeCol.c][247]
  Entry:
  Statement = 0x18fb3a0
  Column Number = 4
  Column Name = 0x7fffce187ca0
  Buffer Length = 31
  Name Length = 0x7fffce187de4
  Data Type = 0x7fffce187de8
  Column Size = 0x7fffce187d80
  Decimal Digits = 0x7fffce187dec
  Nullable = 0x7fffce187df0
[ODBC][24984][1390400782.066581][SQLDescribeCol.c][497]
  Exit:[SQL_SUCCESS]               
  Column Name = [col4]               
  Data Type = 0x7fffce187de8 -> 12               
  Column Size = 0x7fffce187d80 -> 0               
  Decimal Digits = 0x7fffce187dec -> 0               
  Nullable = 0x7fffce187df0 -> 1
As you can see, the Column Size is returned as 0.
Here is the log from the dg4odbc
hoadaMOD bit-values found (0x200:TREAT_AS_CHAR,0x40:TREAT_AS_NCHAR)
DTY         NULL-OK  LEN  MAXBUFLEN   PR/SC  CST IND MOD NAME
  4 INTEGER Y          4          4   0/  0    0   0   0 col1
12 VARCHAR Y         30         30   0/  0    0   0  200 col2
12 VARCHAR Y         60         60 128/ 30 1000   0  40 col3
12 VARCHAR Y          0          0   0/  0    0   0  200 col4
Exiting hgodscr, rc=0 at 2014/01/22-15:26:22
hostmstr:          0: HOA After hoxdscr
hostmstr:          0: RPC After SQL Bundling
hostmstr:          0: RPC Before Fetch Row
hostmstr:          0: HOA Before hoaftch
Entered hgoftch, cursor id 1 at 2014/01/22-15:26:22
hgoftch, line 130: Printing hoada @ 0x1912900
MAX:4, ACTUAL:4, BRC:100, WHT=5 (SELECT_LIST)
hoadaMOD bit-values found (0x200:TREAT_AS_CHAR,0x40:TREAT_AS_NCHAR)
DTY         NULL-OK  LEN  MAXBUFLEN   PR/SC  CST IND MOD NAME
  4 INTEGER Y          4          4   0/  0    0   0   0 col1
12 VARCHAR Y         30         30   0/  0    0   0  200 col2
12 VARCHAR Y         60         60 128/ 30 1000   0  40 col3
12 VARCHAR Y          0          0   0/  0    0   0  200 col4
Performing delayed open.
SQLBindCol: column 1, cdatatype: -16, bflsz: 4
SQLBindCol: column 2, cdatatype: 1, bflsz: 31
SQLBindCol: column 3, cdatatype: -8, bflsz: 62
SQLBindCol: column 4, cdatatype: 1, bflsz: 1
Entered hgopoer at 2014/01/22-15:26:22
hgopoer, line 233: got native error 0 and sqlstate 01004; message follows...
[Microsoft][ODBC Driver 11 for SQL Server]String data, right truncation {01004}
Exiting hgopoer, rc=0 at 2014/01/22-15:26:22
It appears that the SQLBindCol with column4 only allocates one byte... as the length is 0.
Is there any way to fix this behavior.
I tried various things like adding the "VarMaxAsLong = Yes" in the odbc.ini but with no luck.
Thanks for your help
Patrick

Answer 1

Reproduced:
SQL> select * from "VarLong"@MSODBCSQLSERVER_DG4ODBC_EMGTW_1124_DB;
select * from "VarLong"@MSODBCSQLSERVER_DG4ODBC_EMGTW_1124_DB
ERROR at line 1:
ORA-28500: connection from ORACLE to a non-Oracle system returned this message:
[Microsoft][SQL Server Native Client 11.0]String data, right truncation {01004}
ORA-02063: preceding 2 lines from MSODBCSQLSERVER_DG4ODBC_EMGTW_1124_DB
Other ODBC drivers work:
SQL> select * from "VarLong"@FREETDS_DG4ODBC_EMGTW_11_2_0_4.DE.ORACLE.COM;
      col1 col2
col3
col4
         1 value2
value3
value4
Having a quick look at the trace shows the data type being reported is varchar instead of LongVarchar:
Column:4(c): dtype:12 (VARCHAR), prc/scl:0/0, nullbl:1, octet:0, sign:1, radix:0
The precision and scale are correct for a lonvarchar (-1) data type, but not for a varchar.
this issue should be reported to the ODBC vendor.
- Klaus