[postgis-tickets] [PostGIS] #2898: Define a guideline for function cost

[PostGIS]

#2898: Define a guideline for function cost
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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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Comment(by strk):

 The guideline example above is completely off, though.
 Here are some real numbers:
 {{{
           noop : Total runtime: 19523.492 ms (full deserialize/serialize)
    st_envelope : Total runtime: 18411.870 ms (header slice)
  st_convexhull : Total runtime: 18104.542 ms
          plain : Total runtime: 51.341 ms (???)
 }}}

 The times were taken running queries against a ~180k rows raster coverage.
 The "plain" is a "SELECT rast FROM ...".
 The "noop" is a "SELECT postgis_noop(rast) FROM ...".

 The difference between "plain" and "noop" is impressive!!

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2898#comment:2>
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