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From "David Smiley (" <>
Subject Re: difference between geospatial search from database angle and from solr angle
Date Thu, 07 Apr 2011 04:42:04 GMT
    Geospatial search in Lucene/Solr is of course implemented based on
Lucene's underlying index technology. That technology was originally just
for text but it's been adapted very successfully for numerics and querying
ranges too. The only mature geospatial field type in Solr 3.1 is LatLonType
which under the hood is simply a pair of latitude & longitude numeric
fields.  There really isn't anything sophisticated (geospatially speaking)
in Solr 3.1. I'm not sure what sort of geospatial DB research you have in
mind but I would expect other systems would be free to use an indexing
strategy designed for spatial such as "R-Trees". Nevertheless, I think
Lucene offers the underlying primitives to compete with systems using other
technologies.  Case in point is my patch SOLR-2155 which indexes a single
point in the form of a "geohash" at multiple resolutions (geohash lengths
AKA spatial prefixes / grids) and uses a recursive algorithm to efficiently
query an arbitrary shape.  It's quite fast and bests LatLonType already; and
there's a lot more I can do to make it faster.
    This is definitely a field of interest and a growing one in the
Lucene/Solr community.  There are even some external spatial providers
(JTeam, MetaCarta) and I'm partnering with other individuals to create a new
one.  Expect to see more in the coming months.  If you're looking for some
specific geospatial capabilities then let us know.

~ David Smiley 

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