[GRASS-dev] [GRASS GIS] #2131: Terrible performance from v.what.rast due to per-iteration db_execute

[GRASS GIS]

#2131: Terrible performance from v.what.rast due to per-iteration db_execute
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 Reporter:  hamish                   |       Owner:  grass-dev@…              
     Type:  defect                   |      Status:  new                      
 Priority:  major                    |   Milestone:  6.4.4                    
Component:  Database                 |     Version:  svn-develbranch6         
 Keywords:  v.what.rast, db_execute  |    Platform:  Linux                    
      Cpu:  x86-64                   |  
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Comment(by hamish):

 Replying to [ticket:2131 hamish]:
 > I'm running v.what.rast for 175k query points in 6.x. It's taking a
 horribly long time.
 > With debug at level 1 it shows that it gets done with the query
 processing and
 > on to the "Updating db table" stage in less than 1 second. Over an *hour
 > later* I'm still waiting for the dbf process, which is running at 99%
 cpu! This
 > is a fast workstation too.
 ...
 > in trunk it takes about 6 seconds to complete the 100k random
 > points, I'm not seeing anything obvious in the module changelog,
 > so I guess something in the libraries got fixed? any hints?

 actually trunk is pretty bad too. v.db.addtable takes a couple of minutes
 to read the categories (the first half is reasonably quick, but then it
 slows down more and more), and then v.what.rast after running for 13
 minutes is only 9% done. (with the new print instead of update DB flag it
 takes only 0.347s to complete)


 any ideas?

 thanks,
 Hamish

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2131#comment:1>
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