On Fri, Oct 28, 2011 at 1:33 PM, Sandro Santilli <[email protected]> wrote: > On Fri, Oct 28, 2011 at 12:23:24PM -0300, Martin Dobias wrote: >> On Fri, Oct 28, 2011 at 4:15 AM, Sandro Santilli <[email protected]> wrote: >> > Would it make sense to abstract provider-specific IDs so that the >> > [0, N-1] range holds for everyone ? >> >> This is actually done within attribute table - we store feature IDs >> for the range [0,N-1] so that we can later access the feature data by >> row number. But that comes at an additional price: the layer has to be >> scanned first in order to obtain the mapping and it has to be updated >> whenever some changes to the layer are done. >> >> What would be the requirements of such provider-specific IDs? What to >> do when a feature is deleted? If we recreate the mapping, some IDs >> stored by users would change, leading to problems if the user stores >> them as references to features. If we keep the original mapping, then >> it may contain holes and therefore the convenient [0, N-1] range would >> not be valid. > > What happens if you delete a feature from a shapefile ?
Apparently OGR only marks the feature as deleted in DBF, other IDs are not changed. Martin _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
