[freetds] bcp broken on TDS 5.0

Lowden, James K LowdenJK at bernstein.com
Mon Apr 26 10:48:56 EDT 2004


> From: Thompson, Bill D (London) [mailto:bill_d_thompson at ml.com]
> Sent: April 26, 2004 7:00 AM
> 
> I don't know why SYBCHAR was added to the is_nullable_type() 
> macro, but I
> assume there was good reason.
> It may be that we need to make a similar, but not identical, 
> distinction for
> other functionality in our code.
> 
> Can you shed any light on this ?

Hi Bill, 

Some light, perhaps.  It was me, as you know, who changed the macro, and I'm sure it was because I discovered much NULL mishandling in bcp data.  It was right around then that I wrote the bcp unit test, to keep things from breaking again.  

I am tempted to invent a SYBCHARN datatype for the purposes of making this evaluation more consistent.  Whenever we're handed a SYBCHAR type from the server, we inspect its nullability and change its type as need be.  On the way out, the reverse.  The FreeTDS code would see SYBCHAR/SYBCHARN, but the server would of course see only SYBCHAR.  

I'm tempted because 1) it's what Sybase should have done in the first place, and 2) it would mean that calls to macros like is_nullable_type() wouldn't have to be followed a by special-case SYBCHAR test everywhere.  What do you and Frediano think?  

I'd also be willing to bet that if you remove SYBCHAR from the is_nullable_type() macro, you'd break src/dblib/unittests/bcp.c in a pretty obvious way that a guy like you could rectify in short order.  I wouldn't stake a lot on that proposition, but it might be worth a try.   

I'm glad you're working on ct-blk.  How's it going?  

Regards, 

--jkl

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