[gdal-dev] OGR SQL performance issue with VRT as a source?

[Laurențiu Nicola]

Looks like it's spending almost all the time in 
OGRLinearRing::isPointInRing and OGRSimpleCurve::getEnvelope.

Adding -dialect sqlite appears to help.

Laurentiu

On Mon, Oct 20, 2025, at 11:47, Andrey VI via gdal-dev wrote:
> Hi all.
> 
> I have found a significant performance drop when using OGR SQL with VRT as a source. Test results with sample data (link <https://drive.google.com/file/d/1pmwTACFtxjbNDpwuqQJXl0pbtGO6RqeJ/view?usp=sharing>, 6,8 MB).
> VRT as a source:
>  
> $ time ogr2ogr -dialect sqlite -sql "SELECT geometry, CAST(ABS(MAX) AS INT) AS depth FROM merged ORDER BY MAX DESC" sample_vrt-sqlite.geojsons sample.vrt
> real    0m3,960s
> user    0m0,037s
> sys     0m0,022s
> $ time ogr2ogr -sql "SELECT CAST(MAX * -1 AS INTEGER) AS depth FROM merged ORDER BY MAX DESC" sample_vrt-ogr.geojsons sample.vrt
> real    3m4,108s
> user    0m0,057s
> sys     0m0,016s
>  
> Shapefile as a source:
> $ time ogr2ogr -dialect sqlite -sql "SELECT geometry, CAST(ABS(MAX) AS INT) AS depth FROM sample ORDER BY MAX DESC" sample_shp-sqlite.geojsons sample.shp
> real    0m3,627s
> user    0m0,036s
> sys     0m0,025s
> $ time ogr2ogr -sql "SELECT CAST(MAX * -1 AS INTEGER) AS depth FROM sample ORDER BY MAX DESC" sample_shp-ogr.geojsons sample.shp
> real    0m3,731s
> user    0m0,052s
> sys     0m0,025s
>  
> Since my VRTs consist of tens and hundreds of Shapefiles, OGR SQL becomes unusable for the specific task given as an example above.
> So I wonder what could be the reason for such a significant drop in performance in this particular case? Or maybe I’m doing something wrong?
> --
> Andrey
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