[freetds] Pending result limitation

Frediano Ziglio freddy77 at gmail.com
Tue Jun 23 04:45:18 EDT 2009

2009/6/23 Sebastien FLAESCH <sf at 4js.com>
> Hi all,
> (I am using ODBC)
> The FAQ talks about an annoying limitation:
> "Why does each connection support only one query at a time?"
> http://www.freetds.org/faq.html#pending
> I believe this is no longer true... can someone confirm?
> I guess this is related to a TDS protocol version... right?
> Thanks!
> Seb

It should be possible to overcome this limitation using MARS which is
currently not supported by FreeTDS. As said many time you can also
overcome this limit using cursors. There is no planning for protocol
7.2 (mssql 2005 which supports MARS) but currently I have patches for
SQL_VARIANT and MSXML on my quilt directory. I think that one of the
greatest limit of protocol 7.2 is the way BLOBs are handled. Even if
you use TEXT/NTEXT/IMAGE and even if TEXTPTR function returns a proper
value it seems that server doesn't send textptr with data type (it
replace with dummy data). This is not a problem for ODBC but is a big
problem for dblib (and perhaps for CTlib) where writetext require to
know textptr. As usual patches, tests, man work and suggestions are
always welcome.

Currently I'm working on:
- UNICHAR on ctlib
- empty string on ctlib
- numeric on dblib
- client charset on freebcp
That is too much to add MARS :)

  Frediano Ziglio

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