Hi Although I agree that the goal of fast opening is a good idea, as discussed on IRC, I'm not sure we need this RFC for the current work plan it contains : * listing the files in the directory can already be skipped by defining GDAL_DISABLE_READDIR_ON_OPEN=YES. But perhaps this could benefit from the mechanism of thread local configuration option * for the GeoTIFF driver, I think the code could be reworked so that collecting the coordinate system is done only when GetProjectionRef() is called. The .aux.xml file could be opened only when GetProjectionRef(), GetGeoTransform() or GetMetadata() are called. * since GDAL 1.6.0, the GDAL VRT driver can avoid opening the underlying datasets if the SourceProperties elements is defined for each SimpleSource. This is done by the gdalbuildvrt driver. So, opening a VRT dataset should be really quick. The underlying datasets are opened only when real data must be read from them.
Currently, one area where we cannot differ the processing is the instanciation of raster bands. The GetRasterBand() method in GDALDataset is not virtual, so they must be instanciated at the dataset opening. But this is probably only an issue for datasets with millions of bands. Best regards, Even Le Wednesday 22 April 2009 21:30:58 Frank Warmerdam, vous avez écrit : > Folks, > > I have drafted a preliminary version of a new RFC for discussion. > > http://trac.osgeo.org/gdal/wiki/rfc25_fast_open > > Feedback is welcome. > > Best regards, _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
