Next, I need to consider only those restaurants that are inside a particular city limit; the rest are of no interest to me. As the city shown in the following map is rectangle in nature, this makes my job easier:

Now, to see whether a geo point is inside a rectangle, we can use the bounding box filter. A rectangle is marked when you feed the top-left point and bottom-right point.

Let's assume that the city is within the following rectangle with the top-left point as X and Y and the bottom-right point as A and B:

curl -XPOST 'http://localhost:9200/restaurants/_search' -d '{
  "query": {
    "filtered": {
      "query": {
        "match_all": {}
      },
      "filter": {
        "geo_bounding_box": {
          "location": {
            "top_left": {
              "lat": 2,
              "lon": 0
            },
            "bottom_right": {
              "lat": 0,
              "lon": 2
            }
          }
        }
      }
    }
  }
}'