[postgis-devel] [PostGIS] #593: [raster] Add a ST_BandIsNoData function

[PostGIS]

#593: [raster] Add a ST_BandIsNoData function
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 Reporter:  pracine         |       Owner:  jorgearevalo 
     Type:  task            |      Status:  assigned     
 Priority:  medium          |   Milestone:  PostGIS 2.0.0
Component:  postgis raster  |     Version:  trunk        
 Keywords:                  |  
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Comment(by jorgearevalo):

 Replying to [comment:11 pracine]:
 > Replying to [comment:8 jorgearevalo]:
 > > Replying to [comment:7 pracine]:
 > > > As you might guess there is no easy way to set the flag in case a
 ST_SetValue would set the last unique pixel withdata of a raster. There
 should be a ST_BandIsNoData(rast, TRUE) that would scan every raster to
 reset the flag if necessary. This function would be slow as it needs to
 scan every pixels. This function would not be called everytime by pixel
 setting functions but just some times by the user (like a VACUUM ANALYSE
 sql command).
 > >
 > > Actually, I've coded the function with that option, just now. The flag
 forces a new checking.
 >
 > By default the function should NOT check every pixel. It should do it
 just when the boolean parameter is set to TRUE, which means "reverify
 every pixels". (I wrote the opposite above. But I think it is better if we
 do it when TRUE).

 Yes, I did it using FALSE as default. Much more sense.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/593#comment:14>
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