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From Erick Erickson <>
Subject Re: [jira] [Commented] (SOLR-2155) Geospatial search using geohash prefixes
Date Tue, 13 Mar 2012 13:24:10 GMT
Be brave, just go for building it <G>...
It's actually surprisingly easy.

Start here:

you should be able to get this all running (assuming
you have svn, ant and a jdk) in about 15 minutes,
exclusive of the checkout time. I was amazed first
time I tried it.

One note: Solr 3.x all go against the 1.5 JDK. It should
work against the 1.6, but note that the release was compiled
with 1.5.....

Applying the patches is patching source code and recompiling


On Tue, Mar 13, 2012 at 12:17 AM, Harley Parks (Commented) (JIRA)
<> wrote:
>    [
> Harley Parks commented on SOLR-2155:
> ------------------------------------
> So, basic question.. perhaps needs to be posted else where.
> I'm working with Solr 3.4, using the GeoHash to store multiple locations for a document.
> if geofilt or geodist doesn't work with the GeoHash, is the only way to add this patch
into solr 3.4?
> I'm using a tomcat and solr, and jumping to 4.0 might be a while, even if it's released
> I'm not real clear how to apply the patch, as I would need basically create the solr.war
file from the source... and compile all of the other sources... painful, but once setup, perhaps
> Ideally, I would have a jar file from the patch, that I drop into the solr/lib and make
the needed changes to the config files.
> So, I'm real interested in getting something stable, so i'm watching the above mentioned
> David Smiley, would you be able to amend your book - Apache Solr 3 ESS, which mentions
solr-2155, to include how to implement this patch? or do I need to get brave, and build the
>> Geospatial search using geohash prefixes
>> ----------------------------------------
>>                 Key: SOLR-2155
>>                 URL:
>>             Project: Solr
>>          Issue Type: Improvement
>>            Reporter: David Smiley
>>         Attachments: GeoHashPrefixFilter.patch, GeoHashPrefixFilter.patch, GeoHashPrefixFilter.patch,
SOLR-2155_GeoHashPrefixFilter_with_sorting_no_poly.patch, SOLR.2155.p3.patch, SOLR.2155.p3tests.patch,,, Solr2155-for-1.0.2-3.x-port.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 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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