How to handle geospatial data in Redis

Overview

Geospatial data in Redis is represented in terms of longitude and latitude. The geospatial data is stored as a sorted set, as it makes it possible to query the items.

Some of the most frequently used commands for geospatial data in Redis are as follows:

The GEOADD command

The GEOADD command is used to add the specified geospatial data to the given key.

Syntax

The syntax is as follows:

GEOADD key longitude latitude member [ longitude latitude member ...]

where:

• key is the name under which the sorted set for geospatial data is registered.
• longitude is the longitude of the location.
• latitude is the latitude of the location.
• member is the member to store.

The GEODIST command

The GEODIST command is used to get the distance between two geospatial members or points in the specified unit.

Syntax

The syntax is as follows:

GEODIST key member1 member2 [ M | KM | FT | MI]

where:

• key is the name under which the sorted set for geospatial data is registered.
• member1 is the first geospatial member or point.
• member2 is the second geospatial member or point.

The following units of distance are supported.

The unit must be one of the following and defaults to meters:

• m for meters.
• km for kilometers.
• mi for miles.
• ft for feet.

The GEOSEARCH command

The GEOSEARCH command is used to return the members of a geospatial populated sorted set that are within the borders of the area specified by a given shape. This command supports searching in circular as well as rectangular areas.

Syntax

The syntax is as follows:

GEOSEARCH key FROMMEMBER member | FROMLONLAT longitude latitude BYRADIUS radius M | KM | FT | MI | BYBOX width height M | KM | FT | MI [ ASC | DESC]

where:

• key is the name under which the sorted set for geospatial data is registered.

The reference center point for querying is provided by either of the following mandatory options:

• FROMMEMBER: This option indicates to use the given member in the sorted set.
• FROMLONLAT: This option indicates to use the given longitude and latitude.

The search shape for querying is provided by either of the following mandatory options:

• BYRADIUS: Search in a circular area according to the given radius.
• BYBOX: Search in a rectangle according to the given height and width.

To sort the returned results, use one of the following options:

• ASC: This option indicates that the results should be sorted in relation to the central point from nearest to farthest.
• DESC: This option indicates that the results should be sorted in relation to the central point from farthest to nearest.

The GEOPOS command

The GEOPOS command is used to get the positions (longitude, latitude) of all the specified members.

Syntax

The syntax is as follows:

GEOPOS key member [member ...]

where:

• key is the name under which the sorted set for geospatial data is registered.
• member is the member whose position has to be retrieved.