FreeTDS Development Group

[Frediano Ziglio <freddyz77 AT tin.it>]

Il gio, 2004-03-25 alle 19:11, M C ha scritto:
> > > > I am playing with Query Analizer as a server emulator.
> > > For blobs, it will accept arbitrary lengths for textptr, less 
> > > than 256 of coarse (my tests were with the MS odbc driver and 
> > > oledb provider so far).
> > > Would you please check the hardcoding in token.cpp,  function 
> > > tds_get_data(), by the line
> > >     if (len == 16) { /*  Jeff's hack */
> > >         tds_get_n(tds, blob_info->textptr, 16);
> > > 
> > > and see if you can afford a dynamic size for that?
> > > I'm not sure if you want to go for the allocation overhead 
> > > though, but some strategy with optimization for len <= 16 might work.
> > > Thanks,
> > > MC
> > >  
> > 
> > ??? how did you send length for textptr ???
> > textptr is not the content of text...
> > 
> > freddy77
> 
> The byte preceeding textptr in the blob is it's length. It is gotten in 
> tds_get_data(),
>         switch (curcol->column_varint_size) {
>         case 4:  /* Its a BLOB... */
> ---->           len = tds_get_byte(tds);
>                 blob_info = (TDSBLOBINFO *) & 
> (current_row[curcol->column_offset]);
> ---->           if (len == 16) { /*  Jeff's hack */
>                         tds_get_n(tds, blob_info->textptr, 16);
>                         tds_get_n(tds, blob_info->timestamp, 8);
> 
> But tested only against 16 in the if (len == 16).
> 
> I take it that textptr works like a bookmark, the server can send anything 
> and the client will send back the same thing when asking for a chunk.
> 
> MC
> 

Simply we never see a field with length(textptr) different from 0 and
16. 0 means NULL, if text is not null textptr is always 16 byte long...

freddy77