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$center

$center

New in version 1.4.

This specifies a circle shape for the $within operator in geospatial queries. To define the bounds of a query using $center, you must specify:

  • the center point, and
  • the radius

Considering the following example:

db.collection.find( { location: { $within: { $center: [ [0,0], 10 ] } } } );

The above command returns all the documents that fall within a 10 unit radius of the point [0,0].

Changed in version 2.2.3: Before 2.2.3, a geospatial index must exist on a field holding coordinates before using any of the geolocation query operators. After 2.2.3, applications may use geolocation query operators without having a geospatial index; however, geospatial indexes will support much faster geospatial queries than the unindexed equivalents.

Note

A geospatial index must exist on a field and the field must hold coordinates before you can use any of the geolocation query operators.

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