[GRASS-dev] Re: [GRASS GIS] #831: v.category options sum, del, and add do nothing

[GRASS GIS]

#831: v.category options sum, del, and add do nothing
--------------------------+-------------------------------------------------
  Reporter:  isaacullah   |       Owner:  martinl         
      Type:  enhancement  |      Status:  new             
  Priority:  major        |   Milestone:  7.0.0           
 Component:  Vector       |     Version:  svn-develbranch6
Resolution:               |    Keywords:  v.category      
  Platform:  All          |         Cpu:  All             
--------------------------+-------------------------------------------------
Comment (by cmbarton):

 The point is that there is currently a module accessible to all users that
 when used as directed will destroy the linkage between a file of vector
 objects and the attribute data that are linked to those objects. If there
 is no connection between the vector file and an attribute table, as was
 the case in GRASS 5, the way v.category works is not at all a problem.

 In the GRASS of today, where the default is to have attribute tables
 linked with vector objects, this is a big problem. Once executed, the
 linkage destruction is irrecoverable. Imagine a file with 10,000 points
 and 10,000 linked records. At the best, running v.category would result in
 hair-tearing crisis. At the worst, the wrong vector objects would become
 imperceptibly linked with the wrong attribute records producing serious
 data corruption.

 I'm not sure how db.execute will help reconnect this either. Once the cats
 in the vector objects are changed, there is no way to reconnect them
 except to inspect them one at a time and redo the data table. In any
 setting with attribute data linked to vector objects, running v.category
 seems very dangerous.

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/831#comment:11>
GRASS GIS <http://grass.osgeo.org>