[Qgis-developer] Correction of QgsOgrProvider implementaion of GDAL 2.0

[Mark Johnson]

>
> I think you should target master only for your changes (and consider only
> GDAL
> >= 2 case). It is unlikely they are appropriate for backporting, or that
> should be considered in a later stage depending on the impact they have.

Since on my older machine, getting master to run properly is problematic,

> I didn't dig up into that but the issue here is with tables with multiple
> geometry columns, right ? In that case, the OGR uri should likely have a
> geometry= parameter so that the right column is selected. Similarly to what
> the spatialite or postgresql providers do.
>
yes, layername contains the geometry column with the syntax needed
for GDALDatasetGetLayerByName

>
> >
> > --
> > Problem 02:
> >
> > Since 2015, new code has been added implementing gdal 2.* specific
> > functions, which will only be included when compiled/built against gdal
> > 2.*.
> >
> > Thus, when QGIS is complied against gdal 2.*, symbols/functions are added
> > - that doe not exist in gdal 1.*.
>
> To me, this is a non issue, or rather an issue we shouldn't try solving. In
> normal user environements this will not happen. This is just an issue for
> us
> developers that might play with multiple versions.
> What we might perhaps eventually want to ensure is that if QGIS is compiled
> with GDAL 2.X, it works reasonably well when running against GDAL 2.Y
> where Y
> >= X. And even that can be painful, because 2.Y can introduce for example
> new
> geometry types not handled in 2.X, so that would oblige to have runtime
> checks
> in addition to compile time checks. Binary distributions of QGIS are
> normally
> recompiled against a new major GDAL version if they will run against it.
>
The runtime check are a part of this solution and the assumption is that
both runtime and compile checks will be needed in the future.

>
> >
> > For QGIS 3.0: gdal 1.* support should be removed.
>
> This is probably reasonable. I guess that all target environments that
> will be
> able to run QGIS 3.0 will have at least GDAL 2.0.
>
Once in place in release-2_18, it will be easy to port to master (QGIS 3.0)
and to remove everything within the runtime/compile checks < 2 that have
been isolated and checked.

>
> Even
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com
>
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