[postgis-devel] Which intersection is faster?

Jorge Arévalo jorgearevalo at libregis.org
Sat Mar 23 10:20:57 PDT 2013


I don't know if this is a naive question, but in ST_Intersects description (http://postgis.net/docs/manual-2.0/RT_ST_Intersects.html) I read:

"Depending on the order that the raster and geometry is passed to ST_Intersects(), the test will operate in either raster-space or geometry-space. If ST_Intersects(raster, ....), the test is in raster-space (the geometry is converted to a raster). If ST_Intersects(geometry, ...), the test is in geometry-space (the raster is converted to a set of pixel polygons)."

My question: in equal conditions, which version should be faster?

ST_Intersects(raster, vector) --> in raster space
ST_Intersects(vector, raster) --> in vector space

Many thanks in advance, 

Jorge Arevalo
Freelance developer


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