On Jul 29, 2010, at 1:07 PM, ext Frank Warmerdam wrote: > Tamas Szekeres wrote: >> Martin, >> >> I didn't follow all conclusions made earlier in this thread, but I don't >> think it makes much sense to enable/disable the special fields since >> those are derived from the attributes of the feature instead of fetching >> the values physically from the data source. For example OGR_STYLE >> corresponds to OGRFeature::GetStyleString() which can provide a >> meaningful value even if the styles are not handled/supported by a >> particular driver. > > Tamas, > > Geometry is generally derived from the physical data source, and knowing > that it can be ommitted can save substantial io and processing. I must > confess this is less obvious with regard to styles. I can *imagine* > styles being expensive to collect and form in some cases but I can't > think of any existing driver collecting the style string is particularly > expensive.
One that occurs to me is the KML driver, where styles may exist seperately from the features; parsing the style KML (and applying all the cascading stylesheets, etc.) could be expensive, and excluding it could save some processing time in theory. In practice, I don't know whether this is the case for the current driver. -- Chris _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
