Re: AW: [OLEDB_DEV] OLE DB Consumer Templates

Hi,
    MS recommends us to use storage object for sending
a BLOB into a data source. However, as I tested, this
way is bad in many cases since your code needs to
create a store object and database needs to recover
binnary data from the store object. You'd better use
in-memory way to send BLOB for faster speed. With use
of in-memory way, the previous two extra steps are
avoided. Therefore, in-memory way is faster. That is
my guess. Test it yourself.

Regards,

Yuancai (Charlie) Ye

--- Rudolf Wiener <[email protected]> wrote:
> Erik,
>
> For reading and writing blobs, which is what you're
> in fact using, I use the
> technologies recommended and stream the data with a
> storage object. The
> macro I use in the accessor is
> BLOB_ENTRY_LENGTH_STATUS. I'm not sure if
> this is the best way to do it because I have the
> impression it slows things
> down a bit. But I haven't had the time yet to look
> into faster alternatives.
>
> If you like I can send you excerpts from my app's
> code.
>
> Regards
> Rudi
>
>   -----Urspr&#40689;gliche Nachricht-----
>   Von: OLEDB_DEV
> [mailto:[email protected]]Im Auftrag von
> Erik
> Valdes
>   Gesendet: Donnerstag, 09. J&#37592;ner 2003 17:22
>   An: [email protected]
>   Betreff: Re: [OLEDB_DEV] OLE DB Consumer Templates
>
>
>   The reason I can't allocate on the stack is that
> my variable can be any
> length.  It essentially boils down to the string
> representation of an xml
> file.  That file can be any size.  When I pass it to
> my SP, the sp's
> parameter is ntext (to allow for any size).   What
> do people do when they
> want to pass XML of unknown length to a SQL Server
> stored procedure?
>
>
>
>   -----Original Message-----
>   From: Peter Moss [mailto:[email protected]]
>   Sent: Thursday, January 09, 2003 7:58 AM
>   To: [email protected]
>   Subject: Re: [OLEDB_DEV] OLE DB Consumer Templates
>
>
>
>   If I remember right, you can't use the macros for
> heap-allocated
> variables.  If you dig into the macro definitions, I
> believe you will find
> that pointers offset from the beginning of 'this'
> are used.  Thus, a
> heap-allocated variable like m_WorkRequest will not
> work.
>
>
>
>   Why can't you just allocate a TCHAR on the stack
> frame of the object, ie,
>
>
>
>   TCHAR m_WorkRequest[257];     // Or 1 + the size
> of your SP parameter size
>
>
>
>   Then you can just use COLUMN_ENTRY.
>
>
>
>   HTH,
>
>   Peter
>
>     -----Original Message-----
>     From: OLEDB_DEV
> [mailto:[email protected]]On Behalf Of
> Erik
> Valdes
>     Sent: Wednesday, January 08, 2003 5:22 PM
>     To: [email protected]
>     Subject: [OLEDB_DEV] OLE DB Consumer Templates
>
>     I'm having trouble implementing an accessor.
> I'm trying to use a
> variable (m_WorkRequest) that's dynamically
> allocated as the variable that's
> bound to a parameter in my accessor (commented line
> below).   The reason I
> need it to be dynamic is that it is XML and can be
> any length.  The stored
> proc's parameter is of ntext type to handle the
> variable length.  However, I
> don't know at compile time how big to make the
> buffer for my parameter in my
> accessor.  What's the proper way to do this?  I've
> tried COLUMN_ENTRY
> (access violation), COLUMN_ENTRY_LENGTH (different
> variations produce
> different errors, but basically I can't set the
> length),
> COLUMN_ENTRY_TYPE_SIZE (similar problems as the
> previous).  I'm running out
> of ideas now.  The code below is just one of many,
> many variations I've
> tried.
>
>
>
>
>
>     class CAddWorkRequest
>
>     {
>
>     public:
>
>        CAddWorkRequest() STD_INIT
>
>        ~CAddWorkRequest()
>
>        {
>
>           if (m_WorkRequest)
>
>              delete [] m_WorkRequest;
>
>        }
>
>        LONG m_RETURNVALUE;
>
>        LPTSTR m_WorkRequest;
>
>        LONG m_lLength;
>
>
>
>        void SetStringParam(LPCTSTR szString,int
> cBytes)
>
>        {
>
>           m_WorkRequest = (LPTSTR) new
> TCHAR[cBytes];
>
>           _tcsncpy(m_WorkRequest,szString,cBytes);
>
>           m_lLength = _tcslen(m_WorkRequest);
>
>        })
>
>
>
>     BEGIN_PARAM_MAP(CAddWorkRequest)
>
>        SET_PARAM_TYPE(DBPARAMIO_OUTPUT)
>
>        COLUMN_ENTRY(1, m_RETURNVALUE)
>
>        SET_PARAM_TYPE(DBPARAMIO_INPUT)
>
>     //
>
COLUMN_ENTRY_TYPE_SIZE(2,DBTYPE_STR,_tcslen(m_WorkRequest),
> m_WorkRequest)
>
>
>
>
>
>     END_PARAM_MAP()
>
>
>
>     DEFINE_COMMAND(CAddWorkRequest, _T("{ ? = CALL
> dbo.AddWorkRequest;1
> (?) }"))
>
>
>
>     };
>
>
>
>     class CAddWorkRequestCommand : public
> CBsDbCommand<CAddWorkRequest>
>
>     {
>
>     };
>
>
>
>     foo (LPTSTR szWor)
>
>     {
>
>
=== message truncated ===


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