FreeTDS Development Group

[Frediano Ziglio <freddyz77 AT tin.it>]

Il ven, 2002-08-30 alle 06:37, James K.Lowden ha scritto:
> All, 
> 
> I tested the dbconvert() tonight.  I thought you might be interested in
> what I found.  
> 
> Executive summary: B+.  No segfaults.  Mostly correct outcomes when the
> return code indicates success.  Unexotic conversions mostly succeed. 
> Failures trigger the error handler with oh-so-helpful messages.  
> 
> You can reproduce my results if you like, by looking at this page:
> 
> http://www.SchemaMania.org/freetds/cvs/freetds/src/dblib/unittests/
> 
> You need: convert_acid.c and eg_handlers.h
> also:   convert_acid.make (a shell script)
> and     convert_acid.output (my results)
> and     killer_query.sql 
> 
> The query returns one row of 18 datatypes.  The program executes a query
> (from stdin) and attempts to convert each value in the result set to every
> known datatype.  It consults dbwillconvert() first, and doesn't attempt to
> convert incompatible types.  
> 
> Anyone think any of this should be in cvs?

Yes and not.
If this can be converted in an automatic test should be better.
Why not process an input file and compare results with an output file ?

> 
> == the results (with TDS 5.0) ==
> 
> Forget Binary, image, numeric, and decimal.  They're mostly broken.  

They are unimplemented... broken seem a fault to me...
How should we convert to binary/image?
Should we just do a memcpy or we should swap some bytes before ??

> 
> input         status  comment
> =====         ======  =======
> char          OK      No numeric/decimal, no money. 
> text, varchar Perfect!
> bit           OK      No numeric/decimal. 
> tinyint               OK      No numeric, image.
> int, smallint OK      No numeric/decimal, image/binary.
> real, float   fair    No numeric, image, integers; maybe money.  
> datetime      OK      No image/binary.
> smalldatetime OK      No image/binary.
> money         fair    No numeric, image, integers.  
> money         wrong   float & real yield -283649471676416.

What are trying to convert? Perhaps is only a precision problem.

> smallmoney    OK      No numeric/decimal, image/binary.       
> smallmoney    odd     201203.04 -> real yields 201203.046875 

No problem. smallmoney has a precision of 32 bit while real has a
precision of only 24 bit (about 8 digit)...

> numeric               broken  char/varchar only. 
> decimal               broken  char/varchar, float/real only.
> timestamp     broken  char/varchar only. 
> image,varbinary       broken  char, text, binary only.  
> 

Same problem for converting to binary/image...

> == conclusions ==
> 
> 0.  Everything can be made into a char/varchar!
> 1.  Money needs attention.  Should convert to int, should correctly
> convert to floating point.  This is just a debugging effort; the code is
> there.  
> 2.  What happened to float -> int? 
> 3.  Numeric/decimal is not ready.  
> 

Perhaps we can convert numeric -> char -> anytype. Poor performance but
better than nothing.

> As far as I'm concerned, 1 & 2 have to work in 0.60.  Numeric is the other
> big hole, but I don't consider it essential.  I know, I've many times said
> "any<->any in 0.60".  I wasn't thinking about legal weird conversions like
> "datetime<->image".  If we crossed those three items off the list (as
> done), I'd consider the job complete.  
> 
> And, if someone wants to make numeric work in 0.60, you've still got a
> couple of weeks! 
> 
> The mere fact that my testing was worth bothering with is evidence of how
> far we've come.  I'm going to return to updating the UG in preparation for
> our release.  As soon as money works, I'll arrange a pre-release.  
> 
> I hope you're having fun.  I sure am.  
> 
> Regards,
> 

freddy77