Article: Q126614
Product(s): Open Database Connectivity (ODBC)
Version(s): WINDOWS:2.0
Operating System(s):
Keyword(s):
Last Modified: 12-JUN-2001
-------------------------------------------------------------------------------
The information in this article applies to:
- Microsoft Open Database Connectivity, version 2.0
-------------------------------------------------------------------------------
SYMPTOMS
========
If you use SQLBindParameter to directly pass more than 32K of data to a SQL
statement against 16-bit desktop database drivers, you will get the following
error message:
SQL_ERROR: Memory allocation failure.
The following is a piece of the code to duplicate the error:
//data source is an access table objtab with only one OLE field.
//16-bit Access driver 2.00.2317 is used
SQLPrepare(hstmt, "insert into objtab(?)", SQL_NTS);
BigObj = AllocateMemory(sizeof(UCHAR) * 32800);
cbBigObj = 32800;
SQLBindParameter(
hstmt, 1, SQL_PARAM_INPUT, SQL_C_BINARY, SQL_C_LONGVARCHAR,
32800, 0, BigObj, 32800, &cbBigObj);
//Prepare the BigObj
SQLExecute(hstmt);
Returns:
SQL Error State:S1001; Native Error Code: 34;
ODBC Error:[Microsoft][ODBC Microsoft Access 2.0 Driver]memory allocation
failure.
NOTE: If cbBigObj is changed to 32750 (with corresponding changes in
SQLBindParameter), SQLExecute will succeed.
CAUSE
=====
The internal buffer for direct parameters passed to the 16-bit desktop database
drivers is limited to 32K.
NOTE: You will actually have a little less than 32K of total parameters, because
some space is taken up by a length byte in the internal buffer.
RESOLUTION
==========
- Use 32-bit drivers if you can.
- Use SQLPutData to send it in installments. Using direct parameters is not
recommended to pass in large data. Instead, you can use data-at-execution
with SQLPutData.
- Use SQLExtendedFetch and SQLSetPos...SQL_ADD, which is faster. Because all of
the parameters are not copied into a separate buffer before being passed into
the internal buffer, you save a memcopy.
Additional query words: C++ Visual Basic MSVC VB Windows NT
======================================================================
Keywords :
Technology : kbAudDeveloper kbODBCSearch kbODBC200
Version : WINDOWS:2.0
Issue type : kbprb
=============================================================================