[postgis-tickets] [PostGIS] #2454: [raster] ST_PixelAsPolygons does not obey exclude_nodata_value=TRUE

[PostGIS]

#2454: [raster] ST_PixelAsPolygons does not obey exclude_nodata_value=TRUE
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 Reporter:  alfred  |       Owner:  dustymugs     
     Type:  defect  |      Status:  assigned      
 Priority:  medium  |   Milestone:  PostGIS Future
Component:  raster  |     Version:  trunk         
 Keywords:          |  
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Comment(by alfred):

 Replying to [comment:9 dustymugs]:
 > > The problem with that is that it increases the query time
 significantly by going over all the pixels (can be thousands of those),
 even that i care only about the ones that have data only.
 > >
 >
 > It will always go over every pixel. How else are you to know what the
 value of a pixel is?
 >
 > > I was hoping that now that this function is implemented in C that this
 will provide boost in the speed, which it seems that it does in general,
 but not for this case.
 > >
 >
 > It was always in C, even in 2.0.

 I am sorry , what i mean is that if you do not believe that this check
 done in C is going to be faster than doing a SQL WHERE check, then
 probably there is no point in having this parameter
 (exclude_nodata_value).

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2454#comment:10>
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