[postgis-tickets] [PostGIS] #2895: Increase cost of ST_ConvexHull(raster)

[PostGIS]

#2895: Increase cost of ST_ConvexHull(raster)
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 Reporter:  strk         |       Owner:  pramsey      
     Type:  enhancement  |      Status:  new          
 Priority:  medium       |   Milestone:  PostGIS 2.2.0
Component:  postgis      |     Version:  trunk        
 Keywords:               |  
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 The cost of ST_ConvexHull(raster) is currently set to 1.
 For comparison ST_ConvexHull(geometry) is 100, and st_intersects(raster,
 raster) is 1000.

 Real world cases have been found where a cost of 100 is not enough for the
 planner to choose a functional index scan for a query using a spatial
 condition on the raster column, while such index scan would take half the
 time (probably due to the pre-computation of the function output). See
 http://lists.osgeo.org/pipermail/postgis-devel/2014-August/024461.html

 Raising it to 200 seems enough for the specific case.


 It's to be determined out to deal with upgrades on function cost changes.


 See #2839 for the change that made the problem more evident.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2895>
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