Hi Group, I think I want your opinion on a query I have written.
The goal is to find the highest value in a DEM, a raster table. The solution I found brings me where I want to go, but it takes 45 seconds on a relatively small (225*259) grid. It looks like it is especially the nested loop on the ST_Value function in the subquery that does take some time. Can you have a look at the query below and tell me if I am on the right track. Or is there an other route I should follow? A full description of my workflow (and the origin of the table used) can be found in 2 blog posts: - http://twiav-tt.blogspot.nl/2012/06/postgis-raster-analysis-find-highest.html - http://twiav-tt.blogspot.nl/2012/06/postgis-raster-analysis-find-highest_24.html This is the query: INSERT INTO france.highest_peak_martinique(height, geom) SELECT height, ST_SetSRID(ST_MakePoint(ST_Raster2WorldCoordX(rast,x), ST_Raster2WorldCoordY(rast,y)),32620) as geom FROM (SELECT ST_Value(rast, hor.n, ver.n) AS height, hor.n AS x, ver.n AS y FROM generate_series(1,225) as hor(n), generate_series(1,259) as ver(n), france.mnt_martinique ORDER BY height DESC LIMIT 1) AS highest_cell_value, france.mnt_martinique; Please let me know what you think. TIA, Egge-Jan
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