On 27 March 2012 16:09, Denis Rouzaud <denis.rouz...@gmail.com> wrote: > Hi Nicolas, > > Thanks again. > > Well, this working, but this not performant... > > Based on your suggestion, I tried this: > in view1: > ST_Multi(ST_LineMerge(ST_Union(wkb_geometry)))::geometry(MultiLineString,21781) > AS wkb_geometry > > Then in view2: > ST_CollectionHomogenize(wkb_geometry)::geometry(LineString,21781) AS > wkb_geometry > FROM view1 > WHERE ST_NumGeometries(wkb_geometry) = 1; > > And I can detect problems by doing: > SELECT id FROM view1 WHERE ST_NumGeometries(wkb_geometry) != 1; > > > But this is slowing down a lot. > I think that the ST_CollectionHomogenize is not the right way. Is there a > better function to transform multiline to line if I am sure I only have > lines? >
I did not know this function. 2.0 ? You can simply do: st_setsrid(ST_geometryN(wkb_geometry), 21781) AS wkb_geometry FROM view1 WHERE ST_NumGeometries(wkb_geometry) = 1; If geoms come from linemerge, no need to cast to a linestring. It is already one. Nicolas _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
