[gdal-dev] Question about GeoPackage and views

[Even Rouault]

On mercredi 1 novembre 2017 12:57:35 CET Rahkonen Jukka (MML) wrote:
> Hi,
> 
> I was reading the GeoPackage standard and only now read carefully the
> requirement 29
> 
> "A GeoPackage MAY contain tables or updateable views containing vector
> features. Every such feature table or view in a GeoPackage SHALL have a
> column with column type INTEGER and 'PRIMARY KEY AUTOINCREMENT' column
> constraints"
> 
> Should I really read this so that GeoPackage MUST NOT contain non-updateable
> views, or at least they cannot be included in the standard  gpkg_contents
> and gpkg_geometry_columns tables but used only through some extension?

Hi Jukka,

Good question. There's a related ticket in
https://github.com/opengeospatial/geopackage/issues/207

Anyway it is difficult currently to support updatable or non-updatable views since there's no 
reliable way to figure out the FID column for a view, as there's no equivalent of Spatialite's 
views_geometry_columns

GDAL's implementation:
"""Starting with GDAL 2.2, in the case of the columns in the SELECT clause of the view acts a 
integer primary key, then it can be recognized by OGR as the FID column of the view, 
provided it is renamed as OGC_FID. Selecting a feature id from a source table without 
renaming will not be sufficient, since due to joins this feature id could appear several times. 
Thus the user must explicitly acknowledge that the column is really a primary key."""

Even

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