[gdal-dev] RFC 29: OGR Set Desired Fields

[Jez Walters]

Martin,


Although I take your point about the interface not affecting ogr2ogr, surely the potential speed boost is worth extending to this utility too - or would that be a separate ticket?  I for one would welcome improving the performance of ogr2ogr using the approach you have suggested - when I launch the current trunk development version of ogr2ogr from VBScript it gets stuck in an infinite loop trying to process a 5x5km vector data chunk.

This issue aside, won't the fact that field names are constant but field numbers are not in the OS MasterMap vector data present problems for those that wish to programmatically parse the OS GML using your interface?


Regards,


Jez


-----Original Message-----
From: gdal-dev-bounces at lists.osgeo.org [mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Martin Dobias
Sent: Wednesday 21 July 2010 10:44
To: Jez Walters
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] RFC 29: OGR Set Desired Fields

Hi Jez

On Wed, Jul 21, 2010 at 10:43 AM, Jez Walters <Jez.Walters at ipl.com> wrote:
> Martin,
>
>
> When I convert Ordnance Survey MasterMap GML to ESRI Shapefiles using ogr2ogr, I'm getting different field numbers for the same field name in different GML chunk files.  Apologies if I have the wrong end of the stick, but wouldn't your proposed interface therefore require me to invoke ogr2ogr differently for each different GML chunk file, in order to accommodate the different field ordering?

The proposed API addition doesn't affect the behaviour of existing applications such as ogr2ogr.

> Assuming I'm right, wouldn't it be more useable for the interface to use field names rather than numbers?

IMHO for developers it's easier to work with indexes of fields rather than with their names.

Regards
Martin
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