[[lat-lon]]
=== `lat_lon`

deprecated[5.0.0, ????????]
// https://github.com/elastic/elasticsearch/issues/19792

<<geo-queries,Geo-queries>> are usually performed by plugging the value of
each <<geo-point,`geo_point`>> field into a formula to determine whether it
falls into the required area or not. Unlike most queries, the inverted index
is not involved.

Setting `lat_lon` to `true` causes the latitude and longitude values to be
indexed as numeric fields (called `.lat` and `.lon`). These fields can be used
by the <<query-dsl-geo-bounding-box-query,`geo_bounding_box`>> and
<<query-dsl-geo-distance-query,`geo_distance`>> queries instead of
performing in-memory calculations. So this mapping:

[source,js]
--------------------------------------------------
PUT my_index
{
  "mappings": {
    "my_type": {
      "properties": {
        "location": {
          "type": "geo_point",
          "lat_lon": true <1>
        }
      }
    }
  }
}
--------------------------------------------------
// CONSOLE
// TEST[warning:geo_point lat_lon parameter is deprecated and will be removed in the next major release]
<1> Setting `lat_lon` to true indexes the geo-point in the `location.lat` and `location.lon` fields.

With this document:

[source,js]
--------------------------------------------------
PUT my_index/my_type/1?refresh
{
  "location": {
    "lat": 41.12,
    "lon": -71.34
  }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

Allows this query:

[source,js]
--------------------------------------------------
GET my_index/_search
{
  "query": {
    "geo_distance": {
      "location": {
        "lat": 41,
        "lon": -71
      },
      "distance": "50km",
      "optimize_bbox": "indexed" <1>
    }
  }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]
// TEST[warning:Deprecated field [optimize_bbox] used, replaced by [no replacement: `optimize_bbox` is no longer supported due to recent improvements]]
<1> The `indexed` option tells the geo-distance query to use the inverted index instead of the in-memory calculation.

Whether the in-memory or indexed operation performs better depends both on
your dataset and on the types of queries that you are running.

NOTE: The `lat_lon` option only makes sense for single-value `geo_point`
fields. It will not work with arrays of geo-points.