Docs Home → Develop Applications → MongoDB Manual
Geospatial Indexes
On this page
Geospatial indexes support queries on data stored as GeoJSON objects or legacy coordinate pairs. You can use geospatial indexes to improve performance for queries on geospatial data or to run certain geospatial queries.
MongoDB provides two types of geospatial indexes:
2dsphere Indexes, which support queries that interpret geometry on a sphere.
2d Indexes, which support queries that interpret geometry on a flat surface.
To learn more about geospatial data and query operations, see Geospatial Queries.
Use Cases
If your application frequently queries a field that contains geospatial data, you can create a geospatial index to improve performance for those queries.
Certain query operations require a geospatial index.
If you want to query with the $near or $nearSphere
operators or the $geoNear aggregation stage, you must create
a geospatial index. For details, see Geospatial Query Operators and
Geospatial Aggregation Stage.
For example, consider a subway collection with documents containing
a location field, which specifies the coordinates of subway stations
in a city. You often run queries with the $geoWithin operator
to return a list of stations within a specific area. To improve
performance for this query, you can create a geospatial index
on the location field. After creating the index, you can query
using the $near operator to return a list of nearby stations,
sorted from nearest to farthest.
Indexing commonly queried fields increases the chances of covering those queries. Covered queries are queries that can be satisfied entirely using an index, without examining any documents. This optimizes query performance.
Get Started
To create a geospatial index and run geospatial queries, see:
Details
This section describes details about geospatial indexes.
Sharded Collections
You can't use a geospatial index as a shard key when sharding a collection. However, you can create a geospatial index on a sharded collection using a different field as the shard key.
You can use geospatial query operators and aggregation stages to query for geospatial data on sharded collections.
Prior to MongoDB 4.0, $near and $nearSphere queries are not supported
for sharded collections. Instead, you can use the $geoNear
aggregation stage or the geoNear command.
Covered Queries
Geospatial indexes can't cover a query.
Spherical Queries
Using a 2d index for queries on spherical data
can return incorrect results or an error. For example,
2d indexes don't support spherical queries that wrap
around the poles.
However, you can use the 2dsphere index for both spherical queries
and two-dimensional queries. For two-dimensional queries, the
2dsphere index converts data stored as legacy coordinate pairs to
the GeoJSON Point type.
Learn More
For sample geospatial query operations, see Geospatial Query Examples.