Changes between Version 11 and Version 12 of FDORfc55


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Timestamp:
Jun 1, 2011, 1:11:28 PM (13 years ago)
Author:
danstoica
Comment:

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  • FDORfc55

    v11 v12  
    1 = FDO RFC 55 - Convert !FdoDecimal(p,0) datatype to !FdoInt32 for SHP Provider =
     1= FDO RFC 55 - Convert FdoDecimal(p,0) datatype to FdoIntXX for SHP Provider =
    22
    33This page contains an change request (RFC) for the FDO Open Source project. 
    … …  
    3333      >> If you execute an IApplySchema on a SHP connection. Any Int32 properties in any class definitions inside the schema (to be applied) will be converted to Decimal properties once the schema has been applied. This does not happen if the Int32 property happens to be an Identity property. <<
    3434
    35 For further clarification "will be converted to Decimal properties" refer to !FdoDecimal properties.
     35For further clarification "will be converted to Decimal properties" refer to FdoDecimal properties.
    3636
    37 Note storing !FdoInt32 as Decimals is expected since by specification DBF files natively do not have an integer type, but only DECIMAL(precision, scale) datatype. The same apply to double and single precision datatypes. Hence a !FdoInt32 is mapped to a DECIMAL(11, 0) column type.
     37Note storing !FdoInt32 as Decimals is expected since by specification DBF files natively do not have an integer type, but only DECIMAL(precision, scale) datatype. The same apply to double and single precision datatypes. Hence a integer type like FdoInt32 is mapped to a DECIMAL(11, 0) column type.
    3838
    39 The impact is on Describe Schema when currently a !FdoDecimal is returned for a DECIMAL column even in the cases when the scale is zero and most probably the original type was a !FdoInt32.
     39The impact is on Describe Schema when currently a FdoDecimal is returned for a DECIMAL column even in the cases when the scale is zero and most probably the original type was a FdoInt32.
    4040
    41 This RFC is required since reading back a !FdoInt32 instead of a !FdoDecimal is a change in behavior.
     41This RFC is required since reading back a FdoInt32 instead of a FdoDecimal is a change in behavior. For completitude FdoInt16 and FdoInt64 have been added to the scope.
    4242
    4343== Proposed Solution ==
    … …  
    4545Modify the FDO SHP provider:
    4646
    47     * the DBF to FDO datatype mapping (physical to logical conversion) needs a small refinement. In the case of DECIMAL(precision, scale) check the scale value. When the scale is 0 (zero) then return an !FdoInt32 rather than an !FdoDecimal. Note SHP doesn't support !FdoInt64 or !FdoInt16 datatypes therefore the mapping to !FdoInt32 is unique.
     47    * the DBF to FDO datatype mapping (physical to logical conversion) needs a small refinement. In the case of DECIMAL(precision, scale) check the scale value. When the scale is 0 (zero) and depending on the precision return FdoInt16, FdoInt32 or FdoInt64 rather than an FdoDecimal. Note SHP provider currently does not support FdoInt64 or FdoInt16 datatypes and they have to be added to the schema capabilities.
    4848
     49Below the mapping between FdoIntX datatypes and Decimal precision:
    4950
    5051|| Fdo type ||  precision ||                    range                                ||
    … …  
    5354|| FdoInt64 ||  12...20   || -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 ||
    5455
    55  
     56Note: beyond the FdoInt64 range the current behaviour will be preserved, i.e. the property type will remain FdoDecimal and a data reader will return a Double.
    5657
    5758== Implications ==
    5859
    59      * In the case of physical DECIMAL(precision, scale) column the corresponding logical FDO property type will be set according to the scale. The caller must expect either a !FdoDecimal or a !FdoInt32 when reading a SHP schema.
     60     * In the case of physical DECIMAL(precision, scale) column the corresponding logical FDO property type will be set according to the scale. The caller must expect either a FdoDecimal or a FdoIntX when reading a SHP schema.
    6061
    61     * This is a behavior change for the SHP provider. Before this change, SHP would return only !FdoDecimal for all numerical FDO types. It would never return an !Int32 except for the identity property (which actually is not stored).
     62    * This is a behavior change for the SHP provider. Before this change, SHP would return only FdoDecimal for all numerical FDO types. It would never return an FdoIntX except for the identity property (which actually is not stored).
    6263
    63     * The provider will return a !FdoInt32 even for properties which originally were DECIMAL(p, 0). This issue can be mitigated by noting the SHP provider already does silent corrections on the fly in certain cases, like truncating the property names when found too long (both on reading and writing).
     64    * The provider will return a FdoIntX even for properties which originally were DECIMAL(p, 0). This issue can be mitigated by noting the SHP provider already does silent corrections on the fly in certain cases, like truncating the property names when found too long (both on reading and writing).
    6465
    6566== Test Plan ==
    6667
    67     * Enhance the unit test and add roundtripping fidelity tests for !FdoInt32 properties.
     68    * Enhance the unit test and add roundtripping fidelity tests for FdoInt16, FdoInt32 and FdoInt64 properties.
    6869 
    6970== !Funding/Resources ==