<HTML><BODY><div>Hi all.</div><div><div><br><span lang="en"><span><span>I have found a significant performance drop when using OGR SQL with VRT as a source. Test results with sample data (<a href="https://drive.google.com/file/d/1pmwTACFtxjbNDpwuqQJXl0pbtGO6RqeJ/view?usp=sharing">link</a>, 6,8 MB).</span></span></span></div><div><span lang="en"><span><span>VRT as a source:</span></span></span></div><div><div> </div><div>$ 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</div><div>real 0m3,960s</div><div>user 0m0,037s</div><div>sys 0m0,022s<div><div><div>$ time ogr2ogr -sql "SELECT CAST(MAX * -1 AS INTEGER) AS depth FROM merged ORDER BY MAX DESC" sample_vrt-ogr.geojsons sample.vrt</div><div>real 3m4,108s</div><div>user 0m0,057s</div><div>sys 0m0,016s</div><div> </div></div></div></div>Shapefile as a source:<div>$ 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</div><div>real 0m3,627s</div><div>user 0m0,036s</div><div>sys 0m0,025s</div><div>$ time ogr2ogr -sql "SELECT CAST(MAX * -1 AS INTEGER) AS depth FROM sample ORDER BY MAX DESC" sample_shp-ogr.geojsons sample.shp</div><div>real 0m3,731s</div><div>user 0m0,052s</div><div>sys 0m0,025s</div><div> </div><div><span lang="en"><span><span>Since my VRTs consist of tens and hundreds of Shapefiles, OGR SQL becomes unusable for the specific task given as an example above.</span></span></span></div><div><span lang="en"><span><span>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?</span></span></span></div></div></div><div>--<br>Andrey</div></BODY></HTML>