[postgis-devel] [PostGIS] #2024: raster: ST_Union is buggy

PostGIS trac at osgeo.org
Thu Oct 4 20:26:44 PDT 2012

#2024: raster: ST_Union is buggy
  Reporter:  robe     |       Owner:  dustymugs    
      Type:  defect   |      Status:  closed       
  Priority:  blocker  |   Milestone:  PostGIS 2.1.0
 Component:  raster   |     Version:  trunk        
Resolution:  fixed    |    Keywords:               

Comment(by robe):


 Not following you.  You mean instead of 100x100 chunked tiles, I don't
 chunk and see how it handles the original 5000x5000 tile I have.  I do
 have about 12GB of aerial data loaded (well that's the size of my schema
 backup). Those are chunked 50x50 though.

 I think our proposition of suitable tile sizes will change a bit with
 C-based functions, it will be less sensitive to size of tile and I expect
 it to be more of a linear process.  To me the issue with the plpgsql is
 not so much the number of
 pixels it had to go thru, but the fact it had to create a copy for each
 raster for each iteration.

 I'm going to test next just chunking 1000x1000 (using the same tile) and
 do the same test compare. I have some DEMs, but I always choose aerials
 for testing since I can spot check an issue by eye much easier.

Ticket URL: <http://trac.osgeo.org/postgis/ticket/2024#comment:22>
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