$near

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Definition定义

$near

Specifies a point for which a geospatial query returns the documents from nearest to farthest. The $near operator can specify either a GeoJSON point or legacy coordinate point.

$near requires a geospatial index:

  • 2dsphere index if specifying a GeoJSON point,
  • 2d index if specifying a point using legacy coordinates.

To specify a GeoJSON point, $near operator requires a 2dsphere index and has the following syntax:语法如下所示：

{
   <location field>: {
     $near: {
       $geometry: {
          type: "Point" ,
          coordinates: [ <longitude> , <latitude> ]
       },
       $maxDistance: <distance in meters>,
       $minDistance: <distance in meters>
     }
   }
}

If specifying latitude and longitude coordinates, list the longitude first and then latitude:

  • Valid longitude values are between -180 and 180, both inclusive.
  • Valid latitude values are between -90 and 90, both inclusive.

When specifying a GeoJSON point, you can use the optional $minDistance and $maxDistance specifications to limit the $near results by distance in meters:

  • $minDistance limits the results to those documents that are at least the specified distance from the center point.
  • $maxDistance limits the results to those documents that are at most the specified distance from the center point.

To specify a point using legacy coordinates, $near requires a 2d index and has the following syntax:语法如下所示：

{
  $near: [ <x>, <y> ],
  $maxDistance: <distance in radians>
}

When specifying a legacy coordinate, you can use the optional $maxDistance specification to limit the $near results by distance in radians. $maxDistance limits the results to those documents that are at most the specified distance from the center point.

Behavior行为

Special Indexes Restriction

You cannot combine the $near operator, which requires a special geospatial index, with a query operator or command that requires another special index. For example you cannot combine $near with the $text query.

Sharded Collections

Starting in MongoDB 4.0, $near queries are supported for sharded collections.

In earlier MongoDB versions, $near queries are not supported for sharded collections; instead, for sharded clusters, you must use the $geoNear aggregation stage or the geoNear command (available in MongoDB 4.0 and earlier).

Sort Operation

$near sorts documents by distance. If you also include a sort() for the query, sort() re-orders the matching documents, effectively overriding the sort operation already performed by $near. When using sort() with geospatial queries, consider using $geoWithin operator, which does not sort documents, instead of $near.

See also参阅

2d Indexes and Geospatial Near Queries

Examples示例

Query on GeoJSON Data

Important

If specifying latitude and longitude coordinates, list the longitude first and then latitude:

  • Valid longitude values are between -180 and 180, both inclusive.
  • Valid latitude values are between -90 and 90, both inclusive.

Consider a collection places that has a 2dsphere index.

The following example returns documents that are at least 1000 meters from and at most 5000 meters from the specified GeoJSON point, sorted from nearest to farthest:

db.places.find(
   {
     location:
       { $near :
          {
            $geometry: { type: "Point",  coordinates: [ -73.9667, 40.78 ] },
            $minDistance: 1000,
            $maxDistance: 5000
          }
       }
   }
)

Query on Legacy Coordinates

Important

If specifying latitude and longitude coordinates, list the longitude first and then latitude:

  • Valid longitude values are between -180 and 180, both inclusive.
  • Valid latitude values are between -90 and 90, both inclusive.

Consider a collection legacy2d that has a 2d index.

The following example returns documents that are at most 0.10 radians from the specified legacy coordinate pair, sorted from nearest to farthest:

db.legacy2d.find(
   { location : { $near : [ -73.9667, 40.78 ], $maxDistance: 0.10 } }
)