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https://issues.apache.org/jira/browse/SOLR-2155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011653#comment-13011653
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David Smiley commented on SOLR-2155:
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I plan to finish a couple improvements to this patch within 2 weeks time:
distance function queries to work with multi-value, and polygon queries that
span the date line. I've been delayed by some life events (new baby).
Furthermore, I'll try and ensure that the work here is applicable to pure
Lucene users (i.e. sans Solr).
One thing I'm unsure of is how to integrate (or not integrate) existing Lucene
& Solr spatial code with this patch. In this patch I chose to re-use some
basic shape classes in Lucene's spatial contrib simply because they were
already there, but I could just as easily of not. My preference going forward
would be to outright replace Lucene's spatial contrib with this patch. I also
think LatLonType and PointType could become deprecated since this patch is not
only more capable (multiValue support) but faster too. Well with filtering,
sorting is TBD. I'm also inclined to name the field type LatLonGeohashType to
re-enforce the fact that it works with lat & lon; geohash is an implementation
detail. In the future it might even not be geohash, strictly speaking, once we
optimize the encoding.
> Geospatial search using geohash prefixes
> ----------------------------------------
>
> Key: SOLR-2155
> URL: https://issues.apache.org/jira/browse/SOLR-2155
> Project: Solr
> Issue Type: Improvement
> Reporter: David Smiley
> Assignee: Grant Ingersoll
> Attachments: GeoHashPrefixFilter.patch, GeoHashPrefixFilter.patch,
> GeoHashPrefixFilter.patch, SOLR.2155.p3.patch, SOLR.2155.p3tests.patch
>
>
> There currently isn't a solution in Solr for doing geospatial filtering on
> documents that have a variable number of points. This scenario occurs when
> there is location extraction (i.e. via a "gazateer") occurring on free text.
> None, one, or many geospatial locations might be extracted from any given
> document and users want to limit their search results to those occurring in a
> user-specified area.
> I've implemented this by furthering the GeoHash based work in Lucene/Solr
> with a geohash prefix based filter. A geohash refers to a lat-lon box on the
> earth. Each successive character added further subdivides the box into a 4x8
> (or 8x4 depending on the even/odd length of the geohash) grid. The first
> step in this scheme is figuring out which geohash grid squares cover the
> user's search query. I've added various extra methods to GeoHashUtils (and
> added tests) to assist in this purpose. The next step is an actual Lucene
> Filter, GeoHashPrefixFilter, that uses these geohash prefixes in
> TermsEnum.seek() to skip to relevant grid squares in the index. Once a
> matching geohash grid is found, the points therein are compared against the
> user's query to see if it matches. I created an abstraction GeoShape
> extended by subclasses named PointDistance... and CartesianBox.... to support
> different queried shapes so that the filter need not care about these details.
> This work was presented at LuceneRevolution in Boston on October 8th.
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