Yes, it is 2.0
http://postgis.refractions.net/documentation/manual-svn/ST_CollectionHomogenize.html
Well, I am turning around the problem...
I have to do a cast, as I used
ST_Multi(ST_LineMerge(ST_Union(wkb_geometry)))::geometry(MultiLineString,xxx)
in the first view to prevent errors of unconnected lines.
Right now the best solution I have is to let the view being unusable,
and another view to report errors.
This is not very satisfying as if a problem occurs, I cannot use my view
until I fix the geometric errors.
Basically, I need to compute a view with a LineMerge returning
LineString (i.e. leaving away features leading to MultiLineString) and
another view returning IDs of features leading to MULTI.
I thought about using ST_Touches but it only uses two geometries and I
can have more in the LineMerge. No idea what to look for...
Thanks for your help. I could go deeper in the problem!
Greetings
Denis
On 03/27/2012 04:39 PM, Nicolas Ribot wrote:
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
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