Geohashes seem to play nicely to the strengths of an indexing search engine, because you can encode quadrants into a string of characters, and use ngram analysis to compare multiple levels of precision. There's almost no extra work that goes into using geohashes with a term-based index.
That said, they carry a lot of annoying edge cases when determining the adjacency of quadrants, so they're hardly a panacea to geospatial search. Lucene 3 and 4 make a lot of progress in spatial search, but there's still a fair bit of room for improvement.
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Geohashes seem to play nicely to the strengths of an indexing search engine, because you can encode quadrants into a string of characters, and use ngram analysis to compare multiple levels of precision. There's almost no extra work that goes into using geohashes with a term-based index.
That said, they carry a lot of annoying edge cases when determining the adjacency of quadrants, so they're hardly a panacea to geospatial search. Lucene 3 and 4 make a lot of progress in spatial search, but there's still a fair bit of room for improvement.