FreeTDS Development Group

[Frediano Ziglio <freddy77 AT gmail.com>]

2011/9/4 James K. Lowden <jklowden AT freetds.org>:
....
>
> 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.
>

>From protocol 7.2 sql server does NOT sent text ptr back to client.
This is one reason why dblib downgrade to 7.1. TEXT still have text
pointer (you can use TEXTPTR T-SQL function to get it) but doing a
select of a TEXT column you get just a dummy text pointer (useless for
WRITETEXT or similar).

> 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.
>

Regards
  Frediano