Hi, Here are some numbers for demonstrating the efficiency that could be obtained if we had ready made OSM polygons available through a service.
The test data are imported into PostGIS database from the Geofabrik finland.osm.bz2 file with osm2pgsql. The server is a modest Ubuntu 10.04 virtual server with 768 MB of memory. Disk is probably not anything special because the server costs 22 per month. Server is running both the database (PostgreSQL 9.0 with PostGIS 1.5.2) and WFS server (TinyOWS 1.0 release candidate). TinyOWS is running in a slow way on Apache2 server as cgi-bin. Data are also re-projected on-the-fly from EPSG:3067 used in the database into EPSG:4326. I have tried to do everything for avoiding over optimistic results. The test request was wget "http://188.64.1.61/cgi-bin/tinyows?service=wfs&version=1.0.0&request=getfeature&typename=tows:osm_polygon&srsname=EPSG:4326&filter=%3CFilter%20%20xmlns:ogc=%22http://www.opengis.net/ogc%22%3E%3CPropertyIsEqualTo%3E%3CPropertyName%3Etows:natural%3C/PropertyName%3E%3CLiteral%3Ewater%3C/Literal%3E%3C/PropertyIsEqualTo%3E%3C/Filter%3E"; -O osm_polygon_test.gml The dataset statistics about the output of the WFS request above are Number of polygons 53617 Number of holes 14843 Max. holes/polygon 702 Number of vertises 1895074 Size of GML output 61.3 MB In my test the total time from sending the request to closing the connection was 86 seconds. Feel free to verify the test yourself. It would also be interesting to see the numbers about the speed we can reach now when we do not have prebuilt polygons to download. I do not know what might be the fastest alternative. Perhaps to download finland.osm.pbf, sorting out by natural=water tag and importing with osm2pgsql, or? -Jukka Rahkonen- _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
