[gdal-dev] ogr2ogr - geojson to mapInfo - size of .dat become too big

[Even Rouault]

Le mercredi 23 septembre 2015 14:41:53, Maxime Demers a écrit :
> Hi Even,
> 
> Thank you for the suggestion. However, it seems I cannot use such a -sql
> statement on a geojson file. I got the following error with the command
> below:
> 
> ogr2ogr -f "MapInfo File" test.tab points.geojson -sql "select cast(id as
> integer(10)), cast(codecs as character(3)), cast(codeSecteur as
> character(20)), cast(codeWork as character(20)), cast(codePostal as
> character(6)) from points"
> 
> ERROR 1: SELECT from table points failed, no such table/featureclass.

The error message gives a hint of the reason of the error. There's no 
table/layer named "points" in the source file. Do "ogrinfo points.geojson" to 
see the name of the layer.

> 
> However, I have no problem to use the same command to convert a MapInfo
> File to another MapInfo File with the -sql statement. Are you able to
> confirm if its possible to do a -sql statement on a geojson file and if
> yes, do you know why I got this error?
> 
> thank you,
> 
> Maxime Demers
> 
> On Tue, Sep 22, 2015 at 2:47 PM, Even Rouault <even.rouault at spatialys.com>
> 
> wrote:
> > Le mardi 22 septembre 2015 16:07:56, Maxime Demers a écrit :
> > > Hi,
> > > 
> > > I have notice something bad when converting a geojson to mapInfo tab
> > > with ogr2ogr. The .dat which contain the table feature's properties is
> > > getting way too big after conversion.
> > > 
> > > To test, I have converted a mapInfo tab to geojson using:
> > > 
> > > ogr2ogr -f "GeoJSON" test.geojson test.tab
> > > 
> > > and then I converted it back to mapInfo tab using:
> > > 
> > > ogr2pgr -f "MapInfo File" test2.tab test.geojson
> > > 
> > > Before convertion, the .dat of the mapInfo file was 8,75 Mo after
> > > conversion it became 105 Mo.
> > > I dont know if the problem is only when converting geojson to mapInfo
> > 
> > tab.
> > 
> > > What could be the cause of the problem and does a solution exists?
> > 
> > Maxime,
> > 
> > The issue is that when converting from GeoJSON to .tab, the source text
> > fields in GeoJSON have no longer an explicit field width, hence the
> > mapinfo driver fallbacks to 254 characters.
> > 
> > You could workaround with a statement like this :
> > 
> > ogr2ogr  -f "MapInfo File" test2.tab test.geojson -sql "select
> > cast(field1_name as character(field_width)), cast(field2_name as
> > character(field2_width)), ... from layername"
> > 
> > to specify explicit field width.
> > 
> > It would have been great if ogr2ogr had a mode to automate this (I
> > thought there was one already, but can't find it)
> > 
> > Even
> > 
> > --
> > Spatialys - Geospatial professional services
> > http://www.spatialys.com

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