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List:       fdo-users
Subject:    [fdo-users] Wrong datatype mapping for oracle number(xx,0)
From:       orest.halustchak () autodesk ! com (Orest Halustchak)
Date:       2007-12-11 8:21:08
Message-ID: F1AFC33B5AA87C4B85146A00AAF677DE1290D68472 () ADSK-NAMSG-02 ! MGDADSK ! autodesk ! com
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Hi Bruno,

FDO maps number(18,0) to fdo decimal(18,0). This constrains the result to be an 18 \
digit number. Mapping to int64 will cause problems since there are int64 values that \
will not fit into number(18,0). You would end up with insert or update errors with \
valid int64 values.

In C++, fdo decimal is represented using C++ doubles since there is no C++ decimal \
type.

The examples used in the trac is number(38,0), which also doesn't support all int64 \
values. There is a related issue that double doesn't have enough accuracy to support \
38 digits.

There are some other alternatives that could be considered.

(i) Map number(n,0) to the int type that supports at least 'n' digits and include a \
range constraint on the property to restrict the value to +/- n digit numbers.

(ii) Instead of handling fdo decimal in C++ as double, define a Decimal class that \
will hold all necessary digits and implement custom handling of arithmetic operations \
within that class.

Note also that a config file could be used with MapGuide to override mapping of \
columns to other fdo types.

Thanks,
Orest.


-----Original Message-----
From: fdo-users-bounces@lists.osgeo.org [mailto:fdo-users-bounces@lists.osgeo.org] On \
                Behalf Of Bruno Scott
Sent: Tuesday, December 11, 2007 2:42 AM
To: fdo-users@lists.osgeo.org
Subject: [fdo-users] Wrong datatype mapping for oracle number(xx,0)


As referring to Mapguide RFC43
http://www.nabble.com/MapGuide-RFC-43---Support-Search-and-Selection-on-Double-Identity-Properties-to14203388s16610.html


They are fixing something that seems to me a FDO bug.
I think FDO should fix it.

FDO Should map NUMBER(18,0) to int64.

thread in the mapguide forum:
http://www.nabble.com/RFC43---FDO-maps-some-database-types-like-an-Oracle-NUMBER-2838-2C0-29-to-an-Fdo-decimal.-to14248311s16610.html



Bruno
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