FreeTDS Development Group

["James K. Lowden" <jklowden AT freetds.org>]

On Tue, 29 Mar 2011 17:06:20 -0400
<eric.berg AT barclayscapital.com> wrote:

> As you may know there are a few things that do not work properly with
> FreeTDS when used against Sybase, so we'd like to have DBI modules
> which use the Sybase and FreeTDS drivers.  

I don't mean to discourage you from your plan; Sybase's ct-lib is
better for Sybase's servers than FreeTDS's, certainly.  OTOH it's not a
fixable bug unless it's in BUGS.  If you'd post a list of ct-lib issues
that you've identified, we could at least keep track.  

> What I've been asked to do is to port DBD::Sybase to DBD::FreeTDS.  

I don't think that's going to be any fun. at. all.  

What you really, really want is two DBD::Sybase modules, one each
compiled and linked with Sybase and FreeTDS libraries.  Then you want
to turn a knob in DBI to choose which one to load when you
connect.  There is no such knob afaik, although adding one would make
you a hero to the many who have suffered its lack.  

One way to solve this without changing DBI is to use DBD::ODBC for the
FreeTDS driver. From a DBI perspective that might be OK, particularly
because the FreeTDS ODBC implementation is more mature and supports
parameterized queries for Microsoft servers.  (Some vendor-specific
stuff will leak out, no matter what you do.)  

Another way, more similar to what you've been asked to do, would be to
patch DBD::Sybase minimall, just enough so that DBI recognizes it by a
different name e.g. DBD::Ctlib.  All the rest of the code would be the
same, facilitating upgrades if you keep your patch handy.  

HTH.  

--jkl