INF: How to Enable Connection Pooling in an OLE DB Application

• Microsoft Open Database Connectivity, version 3.0
• Microsoft OLE DB, version 1.1

SUMMARY

This article describes how to enable ODBC connection pooling in an OLE DB application.

MORE INFORMATION

An OLE DB application can enable ODBC connection pooling if the OLE DB application is using the OLE DB provider for ODBC. The OLE DB application that uses the ODBC provider is like an ODBC application because the ODBC provider internally calls the ODBC API to perform data manipulation.

The ODBC provider does not expose any property to allow an OLE DB application to enable connection pooling. In order to enable connection pooling, the OLE DB application needs to use the ODBC API to enable connection pooling before using the ODBC provider. Because connection pooling is a process-level attribute, any subsequent connection made through the ODBC provider will be using connection pooling.

The following code demonstrates how an OLE DB application can enable connection pooling:

   SQLAllocEnv(&henv);

   //enable connection pooling
      SQLSetEnvAttr(
         NULL,
         SQL_ATTR_CONNECTION_POOLING,
         (SQLPOINTER)SQL_CP_ONE_PER_DRIVER,
         SQL_IS_INTEGER);

   SQLAllocConnect(henv,&hdbc);

   // connect to the OLE DB ODBC provider
         OleInitialize(NULL);
...
      hr = CoCreateInstance( CLSID_MSDASQL, NULL, CLSCTX_INPROC_SERVER,
         IID_IDBInitialize, (void **)&pIDBInit );
...
      CoUninitialize();
   //finish OLE DB stuff

     SQLFreeConnect(hdbc);
     SQLFreeEnv(henv);

   //disable connection pooling
      SQLSetEnvAttr(
         NULL,  // make process level cursor pooling
         SQL_ATTR_CONNECTION_POOLING,
         (SQLPOINTER)SQL_CP_OFF,
         SQL_IS_INTEGER);