FreeTDS Development Group

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

On Thu, 01 Sep 2011 12:04:22 -0400
Mike Slifcak <slif AT bellsouth.net> wrote:

> Is there a brief description of the new capabilities for 0.91?
> I'm looking particularly for leverage to convince existing 0.82 users
> to upgrade.
On 3 Sep 2011 Mike Slifcak <slif AT bellsouth.net> wrote:
> I recall seeing the announcement.  I was hoping for something more
> detailed

To me, the announcement is a list of things you can look forward to if
you use 0.91.  It is derived from ChangeLog, details therein.  

The best reason to upgrade is support, such as it is.  We provide point
releases -- bug fixes -- as and when problems are reported.  If nothing
else, by using 0.91 you'll be using the most popular version, meaning
any problems you encounter have the greatest likelihood of having been
seen/fixed/worked around by others.  

Problems with prior releases won't see any further attention from the
developers.  When someone reports a problem with an earlier version
since fixed, we always advise upgrading.  

> Also, are there any constructs or uses which should be considered
> 'old' or deprecated, which your team plans to obsolete in upcoming
> releases?  Something akin to a migration guide....

Contrary to what you might expect, No.  The APIs that FreeTDS
implements were first specified over 20 years ago and haven't changed
significantly since the mid-1990s.  

To date, every change to the server and protocol has been additive.
Nowadays Microsoft promises to remove the TEXT datatype[1], a move with
protocol and thus possibly API implications.  

TEXT is unusual in that is has direct protocol support: the client and
server share a "text pointer" that allows the client to update part of
a TEXT column.  My guess is that Microsoft will continue to support TEXT
in the protocol for older clients long after they drop it from the
server.  I can't double-check right now, but I bet that's what happens
today when ISQL.EXE selects from a varchar(max) column.  

Please note how speculative all this is.  The server that does not
support TEXT has yet to be seen, much less released.  Ditto for the
protocol changes.  Any effect on FreeTDS and the applications that use
it are years away.   

Even then, what?  Replacing TEXT with varchar(max) represents a server
change; there was no need to change the SQL merely to change how
TEXT is stored and indexed.  And the problem that TEXT presents to
applications -- updating part of a column -- remains, irrespective of
the name.  Therefore the API will still need to support it even if the
underlying protocol support changes.  

I hope that clarifies things a bit.  In short, there's no migration
guide because there's nothing to migrate.  The new version is fully
compatible with the old version, except with more features and fewer
(or at least different) bugs.  

--jkl

[1]  http://msdn.microsoft.com/en-us/library/ms187993.aspx