[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):

 If I change the postgis_noop implementation to simply return the input
 datum it takes 66ms (vs. ~50ms of the plain timing). Having it simply do
 the DETOAST_DATUM makes it jump again to 18149.952 ms

 It turns out EXPLAIN ANALYZE does not run canonical output functions at
 all, so there's no detoasting performed in a "SELECT rast FROM ..."

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2898#comment:3>
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