Geo search

GeoPointField stores latitude/longitude pairs as a 64-bit encoded value. Geo queries use the BKD tree for fast range and distance filtering.

Index a geo point

var doc = new LeanDocument();
doc.Add(new StringField("id", "london"));
doc.Add(new GeoPointField("location", 51.5074, -0.1278));
writer.AddDocument(doc);

GeoPointField writes two numeric sub-fields internally: location_lat and location_lon. It populates NumericDocValues for sorting and emits a BKD point for spatial queries.

Bounding box

var query = new GeoBoundingBoxQuery(
    "location",
    minLat: 51.0, maxLat: 52.0,
    minLon: -1.0, maxLon: 0.0);

var hits = searcher.Search(query, topN: 20);

Matches documents whose geo point falls inside the rectangle. The query is backed by a BKD range intersection — no full-table scan.

Distance

var query = new GeoDistanceQuery(
    "location",
    centreLat: 51.5074, centreLon: -0.1278,
    radiusMetres: 5000);

var hits = searcher.Search(query, topN: 50);

Filters to documents within radiusMetres of the centre point. Uses a BKD bounding-box approximation followed by an exact Haversine distance check on the shortlist.

Combining with text

Geo queries compose with text queries via BooleanQuery:

var bq = new BooleanQuery.Builder()
    .Add(new TermQuery("category", "restaurant"), Occur.Must)
    .Add(new GeoDistanceQuery("location", 51.5, -0.12, 1000), Occur.Filter)
    .Build();

Use Occur.Filter for geo clauses that should restrict results without affecting the BM25 score.

Encoding

GeoEncodingUtils encodes and decodes lat/lon pairs into the 64-bit Morton-like interleaved representation used internally:

long encoded = GeoEncodingUtils.Encode(51.5074, -0.1278);
(double lat, double lon) = GeoEncodingUtils.Decode(encoded);

You don't normally need these directly — GeoPointField and the geo queries call them automatically.

What is not supported

Polygon, line string, or shape queries (no WKT parsing)
Recursive prefix tree or Spatial4n strategies
Cartesian (XY) shapes
Multi-geo fields per document

If you need full spatial support, consider pre-filtering with bounding box or distance queries and post-processing with a spatial library.