[postgis-devel] [PostGIS] #851: [raster] Numerous ST_Value query cause the memory to grow indefinitely

PostGIS trac at osgeo.org
Wed Apr 20 08:06:11 PDT 2011

#851: [raster] Numerous ST_Value query cause the memory to grow indefinitely
 Reporter:  pracine         |       Owner:  jorgearevalo 
     Type:  defect          |      Status:  assigned     
 Priority:  blocker         |   Milestone:  PostGIS 2.0.0
Component:  postgis raster  |     Version:  trunk        
 Keywords:                  |  

Comment(by jorgearevalo):

 I've done these tests:

 - Execute the query without changes.[[BR]]
 - Simplify RASTER_getPixelValue to return a constant float value. It does
 nothing more.[[BR]]
 - Avoid the RASTER_getPixelValue call and execute this query:

 SELECT x, y FROM generate_series(1, 10) x, generate_series(1, 10) y,

 And I'm getting the '''same memory growth in all cases'''. My table
 srtm_35_04_10x10 has 360000 entries. In my 64 bits machine, with 4GB RAM,
 all queries end, but take about 60-70% of available memory. In a 32 bits
 machine with 1GB RAM, the process is killed (even when I'm not calling
 RASTER_getPixelValue at all)

 So, apparently the problem is not caused by RASTER_getPixelValue. It's
 related with the 36000000 rows postgres has to manage. Has sense?

Ticket URL: <http://trac.osgeo.org/postgis/ticket/851#comment:20>
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