2d Indexes
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2d indexes support queries on data stored as points on a two-dimensional plane. The 2d index is intended for queries on legacy coordinate pairs.
To create a 2d index, specify the string 2d as the index
type:
db.<collection>.createIndex( { <location field> : "2d" } )
You cannot use 2d indexes for queries on GeoJSON objects. To enable queries on GeoJSON objects, use 2dsphere indexes.
Note
When creating a 2d index, the first value (longitude) must
be between -180 and 180, inclusive. The second value (latitude) must be between
-90 and 90, inclusive. However, these default limits can be overridden with the min
and max options on 2d indexes. Unlike
2dsphere index coordinates, 2d indexes values do
not "wrap" around a sphere.
Use Cases
Use a 2d index to query and perform calculation on data represented within a two-dimensional plane. For example:
An application analyzing visual similarities between two art pieces.
A calculator that can perform calculations on two-dimensional graphs.
A mobile game that calculates distances between players on a two-dimensional map.
Get Started
To learn how to create and query 2d indexes, see:
Details
Supported Calculations
2d indexes support calculations on a flat, Euclidean plane.
For spherical geometry calculations, store your data as as GeoJSON objects and use a 2dsphere index to support geospatial queries.
Compound 2d Indexes
You can create compound 2d indexes that reference two fields:
The first field must be the location field. The index constructs queries that first select on this field.
The second field further filters results based on additional criteria.
A compound 2d index can cover queries.
sparse Property
2d indexes are always sparse and
ignore the sparse option. If a
document lacks a 2d index field (or the field is null or an
empty array), MongoDB does not add an entry for the document to the
2d index. For inserts, MongoDB inserts the document but does not
add to the 2d index.
For a compound index that includes a 2d index key along with keys of other types, only the 2d index field determines whether the index references a document.