[Gdal-dev] Struggling with OGR writing model

Frank Warmerdam warmerdam at pobox.com
Sun Feb 18 21:15:32 EST 2007

Andrea Aime wrote:
> Hi all,
> as some of you may know, I'm trying to make a Geotools DataStore 
> wrapping the OGR library.
> I'm having troubles mapping gt2 ways of doing things with OGR ones.
> In Geotools, writing model is basically a streaming update/delete that 
> turns to append once you get to the end of the original file, that is:
> 1 open a writer against a layer
> 2 ask for next feature
> 3 update and write the returned feature, or delete it
> 4 (goto 2)
> When stepping to the next feature returns "false" (that is, end of 
> original file) the writer turns in append mode, that is, allows to add 
> new features to the layer.
> Now, depending on the actual storage, this is implemented by:
> a) using native update/delete capabilities (think dbms or shapefiles),
> b) by writing a new separate layer, and when the writer ends its work, 
> by removing the original and renaming the new temporary one to the old 
> layer name.
> Looking at the OGR api, it seems I can use technique a) when the layer 
> supports random updates and deletes.
> Yet, I don't see a general way to use b). Afaics, I can  create a new 
> temporary layer with a different name, write on it, but when writing 
> finishes, how can I rename the temporary layer to the old name?
> The only way seems to wipe out the old layer, recreate it empty,
> and copy back records from the temporary one: a quite inefficient
> solution for just a rename :-)
> Did I overlook a simpler way?


There is no rename capability.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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