Solr - return documents that are within the radius of multiple points?

Question

I have a set of data, where each entry has a lat/lon coordinate associated with it.

I have the following form:

• textfield that is converted to a lat/lon via geocoding
• 3 select fields, each allowing only a single value, and each value represents a lat/lon coordinate

I would like to return all data that has a lat/lon coordinate within a 50 mile radius of any of the lat/lon points selected in the form. What is the recommended approach to doing this with Solr?

Answer 1

You can use a field type LatLonPointSpatialField for indexing the lat/lon. coordinates. For example, Solr default configset defines the following in its schema, which is sufficient to enable spatial search :

<!-- A specialized field for geospatial search filters and distance sorting. -->
<fieldType name="location" class="solr.LatLonPointSpatialField" docValues="true"/>
<dynamicField name="*_p"  type="location" indexed="true" stored="true"/>

LLPSF supports toggling indexed, stored, docValues, and multiValued. LLPSF internally uses a 2-dimensional Lucene "Points" (BDK tree) index when "indexed" is enabled (the default). When "docValues" is enabled, a latitude and longitudes pair are bit-interleaved into 64 bits and put into Lucene DocValues. The accuracy of the docValues data is about a centimeter.

Then for querying, use the geofilt query parser in a filter query. Matching entries within a circle of the given radius around any of the (multiple) lat/lon points selected means you need to OR multiple {!geofilt} queries, one for each pt. Note that the radial distance d must be specified in kilometers, eg. :

 q=*:*&sfield=coord_p&d=80.4672&fq=({!geofilt pt=x1,y1} OR {!geofilt pt=x2,y2} OR ...)