283 lines
8.4 KiB
Markdown
283 lines
8.4 KiB
Markdown
# Geo spatial search support in bleve
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Latest bleve spatial capabilities are powered by spatial hierarchical tokens generated from s2geometry.
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You can find more details about the [s2geometry basics here](http://s2geometry.io/), and explore the
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extended functionality of our forked golang port of [s2geometry lib here](https://github.com/blevesearch/geo).
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Users can continue to index and query `geopoint` field type and the existing queries like,
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- Point Distance
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- Bounded Rectangle
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- Bounded Polygon
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as before.
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## New Spatial Field Type - geoshape
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We have introduced a field type (`geoshape`) for representing the new spatial types.
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Using the new `geoshape` field type, users can unblock the spatial capabilities
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for the [geojson](https://datatracker.ietf.org/doc/html/rfc7946) shapes like,
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- Point
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- LineString
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- Polygon
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- MultiPoint
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- MultiLineString
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- MultiPolygon
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- GeometryCollection
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In addition to these shapes, bleve will also support additional shapes like,
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- Circle
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- Envelope (Bounded box)
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To specify GeoJSON data, use a nested field with:
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- a field named type that specifies the GeoJSON object type and the type value will be case-insensitive.
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- a field named coordinates that specifies the object's coordinates.
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```
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"fieldName": {
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"type": "GeoJSON Type",
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"coordinates": <coordinates>
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}
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```
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- If specifying latitude and longitude coordinates, list the longitude first and then latitude.
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- Valid longitude values are between -180 and 180, both inclusive.
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- Valid latitude values are between -90 and 90, both inclusive.
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- Shapes would be internally represented as geodesics.
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- The GeoJSON specification strongly suggests splitting geometries so that neither of their parts crosses the antimeridian.
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Examples for the various geojson shapes representations are as below.
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## Point
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The following specifies a [Point](https://tools.ietf.org/html/rfc7946#section-3.1.2) field in a document:
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```
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{
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"type": "point",
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"coordinates": [75.05687713623047,22.53539059204079]
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}
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```
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## Linestring
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The following specifies a [Linestring](https://tools.ietf.org/html/rfc7946#section-3.1.4) field in a document:
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```
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{
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"type": "linestring",
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"coordinates": [
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[ 77.01416015625, 23.0797317624497],
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[ 78.134765625, 20.385825381874263]
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]
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}
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```
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## Polygon
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The following specifies a [Polygon](https://tools.ietf.org/html/rfc7946#section-3.1.6) field in a document:
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```
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{
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"type": "polygon",
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"coordinates": [ [ [ 85.605, 57.207],
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[ 86.396, 55.998],
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[ 87.033, 56.716],
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[ 85.605, 57.207]
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] ]
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}
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```
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The first and last coordinates must match in order to close the polygon.
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And the exterior coordinates have to be in Counter Clockwise Order in a polygon. (CCW)
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## MultiPoint
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The following specifies a [Multipoint](https://tools.ietf.org/html/rfc7946#section-3.1.3) field in a document:
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```
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{
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"type": "multipoint",
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"coordinates": [
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[ -115.8343505859375, 38.45789034424927],
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[ -115.81237792968749, 38.19502155795575],
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[ -120.80017089843749, 36.54053616262899],
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[ -120.67932128906249, 36.33725319397006]
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]
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}
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```
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## MultiLineString
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The following specifies a [MultiLineString](https://tools.ietf.org/html/rfc7946#section-3.1.5) field in a document:
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```
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{
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"type": "multilinestring",
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"coordinates": [
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[ [ -118.31726074, 35.250105158],[ -117.509765624, 35.3756141] ],
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[ [ -118.6962890, 34.624167789],[ -118.317260742, 35.03899204] ],
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[ [ -117.9492187, 35.146862906], [ -117.6745605, 34.41144164] ]
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]
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}
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```
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## MultiPolygon
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The following specifies a [MultiPolygon](https://tools.ietf.org/html/rfc7946#section-3.1.7) field in a document:
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```
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{
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"type": "multipolygon",
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"coordinates": [
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[ [ [ -73.958, 40.8003 ], [ -73.9498, 40.7968 ],
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[ -73.9737, 40.7648 ], [ -73.9814, 40.7681 ],
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[ -73.958, 40.8003 ] ] ],
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[ [ [ -73.958, 40.8003 ], [ -73.9498, 40.7968 ],
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[ -73.9737, 40.7648 ], [ -73.958, 40.8003 ] ] ]
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]
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}
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```
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## GeometryCollection
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The following specifies a [GeometryCollection](https://tools.ietf.org/html/rfc7946#section-3.1.8) field in a document:
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```
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{
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"type": "geometrycollection",
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"geometries": [
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{
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"type": "multipoint",
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"coordinates": [
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[ -73.9580, 40.8003 ],
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[ -73.9498, 40.7968 ],
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[ -73.9737, 40.7648 ],
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[ -73.9814, 40.7681 ]
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]
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},
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{
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"type": "multilinestring",
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"coordinates": [
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[ [ -73.96943, 40.78519 ], [ -73.96082, 40.78095 ] ],
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[ [ -73.96415, 40.79229 ], [ -73.95544, 40.78854 ] ],
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[ [ -73.97162, 40.78205 ], [ -73.96374, 40.77715 ] ],
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[ [ -73.97880, 40.77247 ], [ -73.97036, 40.76811 ] ]
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]
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},
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{
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"type" : "polygon",
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"coordinates" : [
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[ [ 0 , 0 ] , [ 3 , 6 ] , [ 6 , 1 ] , [ 0 , 0 ] ],
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[ [ 2 , 2 ] , [ 3 , 3 ] , [ 4 , 2 ] , [ 2 , 2 ] ]
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]
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}
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]
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}
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```
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## Circle
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If the user wishes to cover a circular region over the earth’s surface, then they could use this shape.
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A sample circular shape is as below.
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```
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{
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"type": "circle",
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"coordinates": [75.05687713623047,22.53539059204079],
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"radius": "1000m"
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}
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```
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Circle is specified over the center point coordinates along with the radius.
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Example formats supported for radius are:
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"5in" , "5inch" , "7yd" , "7yards", "9ft" , "9feet", "11km", "11kilometers", "3nm"
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"3nauticalmiles", "13mm" , "13millimeters", "15cm", "15centimeters", "17mi", "17miles" "19m" or "19meters".
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If the unit cannot be determined, the entire string is parsed and the unit of meters is assumed.
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## Envelope
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Envelope type, which consists of coordinates for upper left and lower right points of the shape
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to represent a bounding rectangle in the format [[minLon, maxLat], [maxLon, minLat]].
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```
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{
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"type": "envelope",
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"coordinates": [
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[72.83, 18.979],
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[78.508,17.4555]
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]
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}
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```
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## GeoShape Query
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Geoshape query support three types/filters of spatial querying capability across those
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heterogeneous types of documents indexed.
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### Query Structure:
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```
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{
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"query": {
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"geometry": {
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"shape": {
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"type": "<shapeType>",
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"coordinates": [[[ ]]]
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},
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"relation": "<<filterName>>"
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}
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}
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}
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```
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*shapeType* => can be any of the aforementioned types like Point, LineString, Polygon, MultiPoint,
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Geometrycollection, MultiLineString, MultiPolygon, Circle and Envelope.
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*filterName* => can be any of the 3 types like *intersects*, *contains* and *within*.
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### Relation
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| FilterName | Description |
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| :-----------:| :-----------------------------------------------------------------: |
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| `intersects` | Return all documents whose shape field intersects the query geometry. |
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| `contains` | Return all documents whose shape field contains the query geometry |
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| `within` | Return all documents whose shape field is within the query geometry. |
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------------------------------------------------------------------------------------------------------------------------
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### Older Implementation
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First, all of this geo code is a Go adaptation of the [Lucene 5.3.2 sandbox geo support](https://lucene.apache.org/core/5_3_2/sandbox/org/apache/lucene/util/package-summary.html).
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## Notes
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- All of the APIs will use float64 for lon/lat values.
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- When describing a point in function arguments or return values, we always use the order lon, lat.
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- High level APIs will use TopLeft and BottomRight to describe bounding boxes. This may not map cleanly to min/max lon/lat when crossing the dateline. The lower level APIs will use min/max lon/lat and require the higher-level code to split boxes accordingly.
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- Points and MultiPoints may only contain Points and MultiPoints.
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- LineStrings and MultiLineStrings may only contain Points and MultiPoints.
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- Polygons or MultiPolygons intersecting Polygons and MultiPolygons may return arbitrary results when the overlap is only an edge or a vertex.
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- Circles containing polygon will return a false positive result if all of the vertices of the polygon are within the circle, but the orientation of those points are clock-wise.
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- The edges of an Envelope follows the latitude and logitude lines instead of the shortest path on a globe.
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- Envelope intersecting queries with LineStrings, MultiLineStrings, Polygons and MultiPolygons implicitly converts the Envelope into a Polygon which changes the curvature of the edges causing inaccurate results for few edge cases.
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