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From "Dag H. Wanvik" <Dag.Wan...@Sun.COM>
Subject Re: DerbyDB truncates the values inserted in a numeric field instead of approximating them
Date Fri, 03 Feb 2006 14:19:26 GMT

Hi Jacopo,

>>>>> "Jacopo" == Jacopo Cappellato <tiz@sastau.it> wrote:

Jacopo> Is there a way to configure the way approximations are done? Is it 
Jacopo> something that should be fixed?

I checked the SQL specification and it says that whether rounding or
truncation is used is implementation defined, so Derby is SQL
compliant when it chooses to do truncation. I guess if you want to use
different data base back-ends, your milage might vary in any case, so
it could be advisable to handle this in process in the application
(not assuming anything about how the db handles this).

Dag



Jacopo> 
Jacopo> Hi all,
Jacopo> my name is Jacopo Cappellato, I'm one of the developers of the OFBiz 
Jacopo> project (www.ofbiz.org), that will soon start the incubation process.
Jacopo> 
Jacopo> OFBiz is using DerbyDb as the default db and it works pretty well even 
Jacopo> if we have found some minor issues.
Jacopo> 
Jacopo> One of these is the way numbers are approximated when inserted in 
Jacopo> numeric fields.
Jacopo> 
Jacopo> Namely, DerbyDB truncates the values inserted in a numeric field instead 
Jacopo> of approximating them 
Jacopo> (http://db.apache.org/derby/docs/10.0/manuals/reference/sqlj132.html).
Jacopo> 
Jacopo> Since the general approach in OFBiz is that of using db approximations 
Jacopo> (instead of doing them in the code), this is not a good thing because 
Jacopo> other databases (e.g. MaxDB/SapDB) perform approximations instead of 
Jacopo> truncations in the same situations.
Jacopo> 
Jacopo> So switching from DerbyDB to another one could lead to different 
Jacopo> calculations.
Jacopo> 
Jacopo> Is there a way to configure the way approximations are done? Is it 
Jacopo> something that should be fixed?
Jacopo> 
Jacopo> Thanks,
Jacopo> 
Jacopo> Jacopo
Jacopo> 
-- 
Dag H. Wanvik
Sun Microsystems, Database Technology Group (DBTG)
Haakon VII gt. 7b, N-7485 Trondheim, Norway
Tel: x43496/+47 73842196, Fax:  +47 73842101

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