MongoDB $ geoIntersects与LineString类型不匹配

Question

I have a Mongo collection on which I am trying to perform a $geoIntersects query.

The data in mongo is in the form of:

{
    "_id" : ObjectId,
    "created_at" : ISODate,
    "sentiment" : 0.631925,
    "yyyy-mm" : "2012-9",
    "lat_lon" : [
        -2.0566385,
        52.84265
    ]
}

Running a $geoIntersects query in the form of:

db.gbSmall.findOne({
    lat_lon: {
        $geoIntersects: {
            $geometry: {
                type: "Point",
                coordinates: [-2.0566385,52.84265]
            }
        }
    }
})

or

db.gbSmall.findOne({
    lat_lon: {
        $geoIntersects: {
            $geometry: {
                type: "LineString",
                coordinates: [[-2.0566385,52.84265],[-3.0566385,52.84265]]
            }
        }
    }
})

both properly return the record; however, if I change the query so the line runs through the point, such as:

db.gbSmall.findOne({
    lat_lon: {
        $geoIntersects: {
            $geometry: {
                type: "LineString",
                coordinates: [[-1.0566385,52.84265],[-3.0566385,52.84265]]
            }
        }
    }
})

the record is not returned.

Does a record have to fall on a point of a geoJSON lineString to be matched, or is there something else wrong with the query I am performing?

Answer 1

If you run the same query in Postgis, you get the answer true.

Select ST_Intersects(ST_GeomFromText('POINT(-2.0566385 52.84265)', 4326),
 ST_GeomFromText('LINESTRING(-1.0566385 52.84265,-3.0566385 52.84265)', 4326));

You also get the same answer for a similar sanity check query:

Select ST_Intersects(ST_GeomFromText('POINT(-2 50)',4326),
 ST_GeomFromText('LINESTRING(-3 50, -1 50)',4326));

whereas both the MongoDB versions return nothing for the equivalent queries you gave above.

To me this looks like a bug. I checked the MongoDB source code and their tests and there isn't one for point on line except with end points. The MongoDB intersects functions found in https://github.com/mongodb/mongo/blob/master/src/mongo/db/geo/geoquery.cpp actually use the 3rd party s2 module to do the actual mathematical intersections, see https://github.com/mongodb/mongo/blob/master/src/third_party/s2/s2latlngrect.cc . That is as far as I have got.

I am not posing this as an answer, as I don't have one, but the formatting is nicer than in comments.