c# 在mongo中查詢經緯度範圍

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#region 索引

//IndexKeysDocument doc = new IndexKeysDocument();//建立索引

//2d 平面座標索引，適用於基於平面的座標計算。也支援球面距離計算，不過官方推薦使用2dsphere索引
//BsonValue value = BsonValue.Create("2d");//建立2d索引

//2dsphere 幾何球體索引，適用於球面幾何運算
//不過，只要座標跨度不太大（比如幾百幾千公裡），這兩個索引計算出的距離相差幾乎可以忽略不計
//BsonValue value = BsonValue.Create("2dsphere");//建立2d索引

//doc.Add("loc", value);//loc為資料庫中2d索引的對象名稱
//table.CreateIndex(doc);//建立索引

#endregion

double y = 26.0623344427;
double x = 119.2916107177;
double maxDistance = 0.5;//單位：公裡（千米）
double earchR = 6378137 / 1000.0;//6378137:地球半徑，單位：米
double distance = maxDistance / earchR;

IMongoQuery query = Query.WithinCircle("loc", x, y, distance, true);
IMongoQuery query1 = Query.Near("loc", x, y, distance, true);

var _location = new GeoJsonPoint<GeoJson2DGeographicCoordinates>(new GeoJson2DGeographicCoordinates(x, y));
IMongoQuery query2 = Query.Near("loc", _location, distance, true);

ConcurrentBag<double> bags = new ConcurrentBag<double>();
double totaletime = 0;
int max = 1000;
Parallel.For(0, max, (i) =>
{
    DateTime start = DateTime.Now;
    var finds = table.Find(query1).AsQueryable().ToList();
   
    double etime = (DateTime.Now - start).TotalSeconds;
    bags.Add(etime);
});

c# 在mongo中查詢經緯度範圍