QGIS » QGIS Application

New description:
pick the attached shapefile. Clone the column "GEOID" to another one or just re-save the shape into another one, with the same CRS or another one, and the original values are changed to "-2147483648".

Note1: DBF specifications says that the integer column is of int4 type (values between -2147483648 to +2147483647) so a dbf column with a value of 2634000031005 seems not respectful of the specifications and I guess can cause issues. QGIS should probably handle better this situation but after all seems not its fault.

See for example here: http://www.postgresql.org/docs/8.1/static/datatype.html

If you need a such large number you must use something more advanced, like spatialite or postgis.

I would vote to close this as invalid and file a ticket to ask a better handling (with warnings) of dbf limits.

New description:

Is not unusual to find shapefiles with field values that are above the limits for the column datatype.

When doing a whatever operation with such vector, the result in that columns is "wrong".

I believe that is necessary to add a warning somewhere to let the user know what is going on.

We also had a problem recently with a shapefile in QGIS. A field of this shapefile was defined with REAL; length 19 and precision 0. The field contained an object_id. An attempt to save/export selected features of the shapefile let all the object_id fields be filled with -2147483648 values.

Did some testing with that field definition (Real, length 19, precision 0) and only the range of values between 2147483647 and -2147483647 seems to be insertable. Beyond that, -2147483648 appears in the fields after saving the table. The object_id in the original shapefile exceeded the mentioned value range. This happened in a field defined as REAL, not INTEGER.

In a field of type REAL defined with length=10 and precision=5 in the same shapefile could be entered a value of 999999999,9999.

Observed also an absurdity with field definitions: e.g. a field definition created in QGIS with REAL, length 10, precision 5, is read by ArcGIS and gvSIG as REAL, length 10, precision 6. That's only a slight difference, but the value should be read the same in all programms, isn't it? By the way: fields defined in QGIS as Integer were read as Double (with scale 0) in ArcGIS. Is that supposed to be normal?

Have included two sample shapefiles.
Test_AttrFieldDefinitions_Point.shp [shapefile created with QGIS]
Test_AttrFieldDefinitions_Point_copy.shp [copy of the shapefile above, performed with ArcGIS; the field created with REAL, length 20, precision 5 was changed to length 19, precision 5]

Would propose a new title "Issue with attribute field definition in a shapefile". A warning for users, if they try to create fields beyond the limits, would be really good.