Geo-Spatial Indexes

The geo-spatial index type in ArangoDB is based on Google S2 . Indexing is supported for a subset of the GeoJSON geometry types as well as simple latitude/longitude pairs.

AQL’s geospatial functions and GeoJSON constructors are described in Geo functions.

You can also perform geospatial searches with ArangoSearch.

Using a Geo-Spatial Index

The geospatial index supports distance, containment, and intersection queries for various geometric 2D shapes. You should mainly be using AQL queries to perform these types of operations. The index can operate in two different modes, depending on if you want to use the GeoJSON data-format or not. The modes are mainly toggled by using the geoJson field when creating the index.

This index assumes coordinates with the latitude between -90 and 90 degrees and the longitude between -180 and 180 degrees. A geo index ignores all documents which do not fulfill these requirements.

GeoJSON Mode

To create an index in GeoJSON mode execute:

collection.ensureIndex({ type: "geo", fields: [ "geometry" ], geoJson: true })

This creates the index on all documents and uses geometry as the attributed field where the value is either a Geometry Object  or a coordinate array. The array must contain at least two numeric values with longitude (first value) and latitude (second value). This corresponds to the format described in RFC 7946 Position .

All documents, that do not have the attribute path or have a non-conforming value in it, are excluded from the index.

A geo index is implicitly sparse, and there is no way to control its sparsity. In case that the index was successfully created, an object with the index details, including the index-identifier, is returned.

For technical details on how ArangoDB interprets GeoJSON objects, see GeoJSON Interpretation. In short: the syntax of GeoJSON is used, but polygon boundaries and lines between points are interpreted as geodesics (pieces of great circles on Earth).

Non-GeoJSON mode

This index mode exclusively supports indexing on coordinate arrays. Values that contain GeoJSON or other types of data are ignored. In the non-GeoJSON mode the index can be created on one or two fields.

The following examples work in the arangosh command shell.

To create a geo-spatial index on all documents using latitude and longitude as separate attribute paths, two paths need to be specified in the fields array:

collection.ensureIndex({ type: "geo", fields: [ "latitude", "longitude" ] })

The first field is always defined to be the latitude and the second is the longitude. The geoJson flag is implicitly false in this mode.

Alternatively you can specify only one field:

collection.ensureIndex({ type: "geo", fields: [ "location" ], geoJson:false })

It creates a geospatial index on all documents using location as the path to the coordinates. The value of the attribute has to be an array with at least two numeric values. The array must contain the latitude (first value) and the longitude (second value).

All documents, which do not have the attribute path(s) or have a non-conforming value in it, are excluded from the index.

A geo index is implicitly sparse, and there is no way to control its sparsity. In case that the index was successfully created, an object with the index details, including the index-identifier, is returned.

In case that the index was successfully created, an object with the index details, including the index-identifier, is returned.

FOR doc IN coll
  FILTER GEO_DISTANCE(doc.geo, GEO_POINT(10, 10)) >= 0
  RETURN doc

Legacy Polygons

Between ArangoDB 3.10 and earlier versions, two things have changed:

• boundaries of polygons are now geodesics and there is no special and inconsistent treatment of “rectangles” any more
• linear rings are interpreted according to the rules and no longer “normalized”

See GeoJSON Interpretation for details.

For backward compatibility, a legacyPolygons option has been introduced for geo indexes. It is relevant for those that have geoJson set to true only. Geo indexes created in versions before 3.10 always implicitly have the legacyPolygons option set to true. Newly generated geo indexes from 3.10 onward have the legacyPolygons option set to false by default. However, you can still explicitly overwrite the setting with true to create a legacy index, but it is not recommended.

A geo index with legacyPolygons set to true uses the old, pre-3.10 rules for the parsing GeoJSON polygons. This allows you to let old indexes produce the same, potentially wrong results as before an upgrade. A geo index with legacyPolygons set to false uses the new, correct and consistent method for parsing of GeoJSON polygons.

If you use a geo index and upgrade from a version below 3.10 to a version of 3.10 or higher, it is recommended that you drop your old geo indexes and create new ones with legacyPolygons set to false.

If you use geojson Analyzers and upgrade from a version below 3.10 to a version of 3.10 or higher, the interpretation of GeoJSON Polygons changes. See the legacy property of the geojson Analyzer.

arangosh Examples

Ensures that a geo index exists:

collection.ensureIndex({ type: "geo", fields: [ "location" ] })

Creates a geospatial index on all documents using location as the path to the coordinates. The value of the attribute has to be an array with at least two numeric values. The array must contain the latitude (first value) and the longitude (second value).

All documents, which do not have the attribute path or have a non-conforming value in it, are excluded from the index.

A geo index is implicitly sparse, and there is no way to control its sparsity.

The index does not provide a unique option because of its limited usability. It would prevent identical coordinate pairs from being inserted only, but even a slightly different location (like 1 inch or 1 cm off) would be unique again and not considered a duplicate, although it probably should. The desired threshold for detecting duplicates may vary for every project (including how to calculate the distance even) and needs to be implemented on the application layer as needed. You can write a Foxx service for this purpose and make use of the Geo-spatial functions in AQL to find nearby locations supported by a geo index.

In case that the index was successfully created, an object with the index details, including the index-identifier, is returned.

To create a geo index on an array attribute that contains longitude first, set the geoJson attribute to true. This corresponds to the format described in RFC 7946 Position 

collection.ensureIndex({ type: "geo", fields: [ "location" ], geoJson: true })

To create a geo-spatial index on all documents using latitude and longitude as separate attribute paths, two paths need to be specified in the fields array:

collection.ensureIndex({ type: "geo", fields: [ "latitude", "longitude" ] })

In case that the index was successfully created, an object with the index details, including the index-identifier, is returned.

Examples

Create a geo index for an array attribute:

db.geo.ensureIndex({ type: "geo", fields: [ "loc" ] });

{ 
  "bestIndexedLevel" : 17, 
  "fields" : [ 
    "loc" 
  ], 
  "geoJson" : false, 
  "id" : "geo/79255", 
  "isNewlyCreated" : true, 
  "legacyPolygons" : false, 
  "maxNumCoverCells" : 8, 
  "name" : "idx_1795421255229243392", 
  "sparse" : true, 
  "type" : "geo", 
  "unique" : false, 
  "worstIndexedLevel" : 4, 
  "code" : 201 
}

Create a geo index for an array attribute:

db.geo2.ensureIndex({ type: "geo", fields: [ "location.latitude", "location.longitude" ] });

{ 
  "bestIndexedLevel" : 17, 
  "fields" : [ 
    "location.latitude", 
    "location.longitude" 
  ], 
  "geoJson" : false, 
  "id" : "geo2/79265", 
  "isNewlyCreated" : true, 
  "legacyPolygons" : false, 
  "maxNumCoverCells" : 8, 
  "name" : "idx_1795421255242874880", 
  "sparse" : true, 
  "type" : "geo", 
  "unique" : false, 
  "worstIndexedLevel" : 4, 
  "code" : 201 
}

Use a geo index with the AQL SORT operation:

var idx = db.geoSort.ensureIndex({ type: "geo", fields: [ "latitude", "longitude" ] });
for (i = -90;  i <= 90;  i += 10) {
  for (j = -180; j <= 180; j += 10) {
    db.geoSort.save({ name : "Name/" + i + "/" + j, latitude : i, longitude : j });
  }
}
var query = "FOR doc in geoSort SORT DISTANCE(doc.latitude, doc.longitude, 0, 0) LIMIT 5 RETURN doc"
db._explain(query, {}, {colors: false});
db._query(query).toArray();

{ 
  "_id" : "geoSort/80683", 
  "_key" : "80683", 
  "_rev" : "_holf4EG--F" 
}
Query String (86 chars, cacheable: true):
 FOR doc in geoSort SORT DISTANCE(doc.latitude, doc.longitude, 0, 0) LIMIT 5 RETURN doc

Execution plan:
 Id   NodeType        Est.   Comment
  1   SingletonNode      1   * ROOT
  7   IndexNode          7     - FOR doc IN geoSort   /* geo index scan, index scan + document lookup */    
  5   LimitNode          5       - LIMIT 0, 5
  6   ReturnNode         5       - RETURN doc

Indexes used:
 By   Name                      Type   Collection   Unique   Sparse   Cache   Selectivity   Fields                        Stored values   Ranges
  7   idx_1795421255275380736   geo    geoSort      false    true     false           n/a   [ `latitude`, `longitude` ]   [  ]            (GEO_DISTANCE([ 0, 0 ], [ doc.`longitude`, doc.`latitude` ]) < "unlimited")

Optimization rules applied:
 Id   RuleName
  1   geo-index-optimizer
  2   remove-unnecessary-calculations-2

43 rule(s) executed, 1 plan(s) created, peak mem [b]: 0, exec time [s]: 0.00022

[ 
  { 
    "_key" : "79981", 
    "_id" : "geoSort/79981", 
    "_rev" : "_holf4Am--B", 
    "name" : "Name/0/0", 
    "latitude" : 0, 
    "longitude" : 0 
  }, 
  { 
    "_key" : "80055", 
    "_id" : "geoSort/80055", 
    "_rev" : "_holf4BC--_", 
    "name" : "Name/10/0", 
    "latitude" : 10, 
    "longitude" : 0 
  }, 
  { 
    "_key" : "79983", 
    "_id" : "geoSort/79983", 
    "_rev" : "_holf4Aq---", 
    "name" : "Name/0/10", 
    "latitude" : 0, 
    "longitude" : 10 
  }, 
  { 
    "_key" : "79907", 
    "_id" : "geoSort/79907", 
    "_rev" : "_holf4AO--_", 
    "name" : "Name/-10/0", 
    "latitude" : -10, 
    "longitude" : 0 
  }, 
  { 
    "_key" : "79979", 
    "_id" : "geoSort/79979", 
    "_rev" : "_holf4Am--A", 
    "name" : "Name/0/-10", 
    "latitude" : 0, 
    "longitude" : -10 
  } 
]

Use a geo index with the AQL FILTER operation:

var idx = db.geoFilter.ensureIndex({ type: "geo", fields: [ "latitude", "longitude" ] });
for (i = -90;  i <= 90;  i += 10) {
  for (j = -180; j <= 180; j += 10) {
    db.geoFilter.save({ name : "Name/" + i + "/" + j, latitude : i, longitude : j });
  }
}
var query = "FOR doc in geoFilter FILTER DISTANCE(doc.latitude, doc.longitude, 0, 0) < 2000 RETURN doc"
db._explain(query, {}, {colors: false});
db._query(query).toArray();

{ 
  "_id" : "geoFilter/82103", 
  "_key" : "82103", 
  "_rev" : "_holf4MW--C" 
}
Query String (89 chars, cacheable: true):
 FOR doc in geoFilter FILTER DISTANCE(doc.latitude, doc.longitude, 0, 0) < 2000 RETURN doc

Execution plan:
 Id   NodeType        Est.   Comment
  1   SingletonNode      1   * ROOT
  6   IndexNode          7     - FOR doc IN geoFilter   /* geo index scan, index scan + document lookup */    
  5   ReturnNode         7       - RETURN doc

Indexes used:
 By   Name                      Type   Collection   Unique   Sparse   Cache   Selectivity   Fields                        Stored values   Ranges
  6   idx_1795421255410647040   geo    geoFilter    false    true     false           n/a   [ `latitude`, `longitude` ]   [  ]            (GEO_DISTANCE([ 0, 0 ], [ doc.`longitude`, doc.`latitude` ]) < 2000)

Optimization rules applied:
 Id   RuleName
  1   geo-index-optimizer
  2   remove-unnecessary-calculations-2

43 rule(s) executed, 1 plan(s) created, peak mem [b]: 0, exec time [s]: 0.00022

[ 
  { 
    "_key" : "81401", 
    "_id" : "geoFilter/81401", 
    "_rev" : "_holf4Iq--C", 
    "name" : "Name/0/0", 
    "latitude" : 0, 
    "longitude" : 0 
  } 
]

Indexed GeoSpatial Queries

The geospatial index supports a variety of AQL queries, which can be built with the help of the geo utility functions. There are three specific geo functions that can be optimized, provided they are used correctly: GEO_DISTANCE(), GEO_CONTAINS(), GEO_INTERSECTS(). Additionally, there is a built-in support to optimize the older geo functions DISTANCE(), NEAR(), and WITHIN() (the last two only if they are used in their 4 argument version, without distanceName).

When in doubt whether your query is being properly optimized, check the AQL explain output to check for index usage.

Query for Results near Origin (NEAR type query)

A basic example of a query for results near an origin point:

FOR x IN geo_collection
  FILTER GEO_DISTANCE([@lng, @lat], x.geometry) <= 100000
  RETURN x._key

or

FOR x IN geo_collection
  FILTER GEO_DISTANCE(@geojson, x.geometry) <= 100000
  RETURN x._key

The function GEO_DISTANCE() always returns the distance in meters, so this query receives results up until 100km.

The first parameter can be a GeoJSON object or a coordinate array in [longitude, latitude] ordering. The second parameter is the document field on that the index was created.

In case of a GeoJSON object in the first parameter, the distance is measured from the centroid of the object to the indexed point. If the index has geoJson set to true, then the distance is measured from the centroid of the object to the centroid of the indexed object. This can be unexpected if not all GeoJSON objects are points, but it is what the index can actually provide.

Query for Sorted Results near Origin (NEAR type query)

A basic example of a query for the 1000 nearest results to an origin point (ascending sorting):

FOR x IN geo_collection
  SORT GEO_DISTANCE([@lng, @lat], x.geometry) ASC
  LIMIT 1000
  RETURN x._key

The first parameter can be a GeoJSON object or a coordinate array in [longitude, latitude] ordering. The second parameter is the document field on that the index was created.

In case of a GeoJSON object in the first parameter, the distance is measured from the centroid of the object to the indexed point. If the index has geoJson set to true, then the distance is measured from the centroid of the object to the centroid of the indexed object. This can be unexpected if not all GeoJSON objects are points, but it is what the index can actually provide.

You may also get results farthest away (distance sorted in descending order):

FOR x IN geo_collection
  SORT GEO_DISTANCE([@lng, @lat], x.geometry) DESC
  LIMIT 1000
  RETURN x._key

Query for Results within a Distance Range

A query which returns documents at a distance of 1km or farther away, and up to 100km from the origin:

FOR x IN geo_collection
  FILTER GEO_DISTANCE([@lng, @lat], x.geometry) <= 100000
  FILTER GEO_DISTANCE([@lng, @lat], x.geometry) >= 1000
  RETURN x

This returns the documents with a GeoJSON value that is located in the specified search annulus.

The first parameter can be a GeoJSON object or a coordinate array in [longitude, latitude] ordering. The second parameter is the document field on that the index was created.

In case of a GeoJSON object in the first parameter, the distance is measured from the centroid of the object to the indexed point. If the index has geoJson set to true, then the distance is measured from the centroid of the object to the centroid of the indexed object. This can be unexpected if not all GeoJSON objects are points, but it is what the index can actually provide.

Note that all these FILTER GEO_DISTANCE(...) queries can be combined with a SORT clause on GEO_DISTANCE() (provided they use the same basis point), resulting in a sequence of findings sorted by distance, but limited to the given GEO_DISTANCE() boundaries.

Query for Results contained in Polygon

A query which returns documents whose stored geometry is contained within a GeoJSON Polygon.

LET polygon = GEO_POLYGON([[[60,35],[50,5],[75,10],[70,35],[60,35]]])
FOR x IN geo_collection
  FILTER GEO_CONTAINS(polygon, x.geometry)
  RETURN x

The first parameter of GEO_CONTAINS() must be a polygon. Other types are not really sensible, since for example a point cannot contain other GeoJSON objects than itself, and for others like lines, containment is not defined in a numerically stable way. The second parameter must contain the document field on that the index was created.

This FILTER clause can be combined with a SORT clause using GEO_DISTANCE().

Note that containment in the opposite direction is currently not supported by geo indexes:

LET polygon = GEO_POLYGON([[[60,35],[50,5],[75,10],[70,35],[60,35]]])
FOR x IN geo_collection
  FILTER GEO_CONTAINS(x.geometry, polygon)
  RETURN x

Query for Results Intersecting a Polygon

A query that returns documents with an intersection of their stored geometry and a GeoJSON Polygon.

LET polygon = GEO_POLYGON([[[60,35],[50,5],[75,10],[70,35],[60,35]]])
FOR x IN geo_collection
  FILTER GEO_INTERSECTS(polygon, x.geometry)
  RETURN x

The first parameter of GEO_INTERSECTS() is usually a polygon.

The second parameter must contain the document field on that the index was created.

This FILTER clause can be combined with a SORT clause using GEO_DISTANCE().