range vs. filter queries

[Ryan McKinley]

Hello-

I'm working on a SearchComponent that should limit results to entries 
within a geographic range.  I would love some feedback to make sure I'm 
not building silly queries and/or can change them to be better.  I have 
four fields:

  <field name="north" type="sfloat" ... />
  <field name="south" type="sfloat" ... />
  <field name="east"  type="sfloat" ... />
  <field name="west"  type="sfloat" ... />

The component looks for a "bounds" argument and parses out the NSEW 
corners.  Currently, I'm building a boolean query and adding that to the 
filter list:

      FieldType ft = req.getSchema().getFieldTypes().get( "sfloat" );

      BooleanQuery range = new BooleanQuery( true );
      range.add( new ConstantScoreRangeQuery( "north", null, 
ft.toInternal(n), true, true ), BooleanClause.Occur.MUST );
      range.add( new ConstantScoreRangeQuery( "south", 
ft.toInternal(s), null, true, true ), BooleanClause.Occur.MUST );
      range.add( new ConstantScoreRangeQuery( "east", null, 
ft.toInternal(e), true, true ), BooleanClause.Occur.MUST );
      range.add( new ConstantScoreRangeQuery( "west", ft.toInternal(w), 
null, true, true ), BooleanClause.Occur.MUST );

essentially, this is:
 +north:[* TO nnn] +south:[sss TO *] +east:[* TO eee] +west:[www TO *]


Would this be better as four individual filters?

Additionally, I could chunk the world into a grid and see index if a 
point exists within a square.  This could potentially cut out many 
results with a simple term query, but I don't know if it is worthwhile 
since I will need to run the points through a range query at the end anyway.

Any thoughts of feedback would be great.

thanks
ryan