6.20. Geospatial Functions
Presto Geospatial functions that begin with the ST_
prefix support the
SQL/MM specification and are compliant with the Open Geospatial Consortium’s
(OGC) OpenGIS Specifications. As such, many Presto Geospatial functions
require, or more accurately, assume that geometries that are operated on are
both simple and valid. For example, it does not make sense to calculate the
area of a polygon that has a hole defined outside of the polygon, or to
construct a polygon from a nonsimple boundary line.
Presto Geospatial functions support the WellKnown Text (WKT) and WellKnown Binary (WKB) form of spatial objects:
POINT (0 0)
LINESTRING (0 0, 1 1, 1 2)
POLYGON ((0 0, 4 0, 4 4, 0 4, 0 0), (1 1, 2 1, 2 2, 1 2, 1 1))
MULTIPOINT (0 0, 1 2)
MULTILINESTRING ((0 0, 1 1, 1 2), (2 3, 3 2, 5 4))
MULTIPOLYGON (((0 0, 4 0, 4 4, 0 4, 0 0), (1 1, 2 1, 2 2, 1 2, 1 1)), ((1 1, 1 2, 2 2, 2 1, 1 1)))
GEOMETRYCOLLECTION (POINT(2 3), LINESTRING (2 3, 3 4))
Use ST_GeometryFromText
and ST_GeomFromBinary
functions to create
geometry objects from WKT or WKB. In WKT/WKB, the coordinate order is
(x, y)
. For spherical/geospatial uses, this implies
(longitude, latitude)
instead of (latitude, longitude)
.
The basis for the Geometry
type is a plane. The shortest path between two
points on the plane is a straight line. That means calculations on geometries
(areas, distances, lengths, intersections, etc) can be calculated using
cartesian mathematics and straight line vectors.
The SphericalGeography
type provides native support for spatial features
represented on “geographic” coordinates (sometimes called “geodetic”
coordinates, or “lat/lon”, or “lon/lat”). Geographic coordinates are spherical
coordinates expressed in angular units (degrees).
The basis for the SphericalGeography
type is a sphere. The shortest path
between two points on the sphere is a great circle arc. That means that
calculations on geographies (areas, distances, lengths, intersections, etc)
must be calculated on the sphere, using more complicated mathematics. More
accurate measurements that take the actual spheroidal shape of the world into
account are not supported.
For SphericalGeography
objects, values returned by the measurement functions
ST_Distance
and ST_Length
are in the unit of meters; values returned by
ST_Area
are in square meters.
Use to_spherical_geography()
function to convert a geometry object to
geography object. For example,
ST_Distance(ST_Point(71.0882, 42.3607), ST_Point(74.1197, 40.6976))
returns 3.4577 in the unit of the passedin values on the euclidean plane,
while
ST_Distance(to_spherical_geography(ST_Point(71.0882, 42.3607)), to_spherical_geography(ST_Point(74.1197, 40.6976)))
returns 312822.179 in meters.
Constructors

ST_AsBinary
(Geometry) → varbinary Returns the WKB representation of the geometry.

ST_AsText
(Geometry) → varchar Returns the WKT representation of the geometry. For empty geometries,
ST_AsText(ST_LineFromText('LINESTRING EMPTY'))
will produce'MULTILINESTRING EMPTY'
andST_AsText(ST_Polygon('POLYGON EMPTY'))
will produce'MULTIPOLYGON EMPTY'
.

ST_GeometryFromText
(varchar) → Geometry Returns a geometry type object from WKT representation.

ST_GeomFromBinary
(varbinary) → Geometry Returns a geometry type object from WKB representation.

ST_LineFromText
(varchar) → LineString Returns a geometry type linestring object from WKT representation.

ST_LineString
(array(Point)) → LineString Returns a LineString formed from an array of points. If there are fewer than two nonempty points in the input array, an empty LineString will be returned. Throws an exception if any element in the array is
null
or empty or same as the previous one. The returned geometry may not be simple, e.g. may selfintersect or may contain duplicate vertexes depending on the input.

ST_MultiPoint
(array(Point)) → MultiPoint Returns a MultiPoint geometry object formed from the specified points. Return
null
if input array is empty. Throws an exception if any element in the array isnull
or empty. The returned geometry may not be simple and may contain duplicate points if input array has duplicates.

ST_Point
(x, y) → Point Returns a geometry type point object with the given coordinate values.

ST_Polygon
(varchar) → Polygon Returns a geometry type polygon object from WKT representation.

to_spherical_geography
(Geometry) → SphericalGeography Converts a Geometry object to a SphericalGeography object on the sphere of the Earth’s radius. This function is only applicable to
POINT
,MULTIPOINT
,LINESTRING
,MULTILINESTRING
,POLYGON
,MULTIPOLYGON
geometries defined in 2D space, orGEOMETRYCOLLECTION
of such geometries. For each point of the input geometry, it verifies that point.x is within [180.0, 180.0] and point.y is within [90.0, 90.0], and uses them as (longitude, latitude) degrees to construct the shape of theSphericalGeography
result.

to_geometry
(SphericalGeography) → Geometry Converts a SphericalGeography object to a Geometry object.
Relationship Tests

ST_Contains
(Geometry, Geometry) → boolean Returns
true
if and only if no points of the second geometry lie in the exterior of the first geometry, and at least one point of the interior of the first geometry lies in the interior of the second geometry.

ST_Crosses
(Geometry, Geometry) → boolean Returns
true
if the supplied geometries have some, but not all, interior points in common.

ST_Disjoint
(Geometry, Geometry) → boolean Returns
true
if the give geometries do not spatially intersect – if they do not share any space together.

ST_Equals
(Geometry, Geometry) → boolean Returns
true
if the given geometries represent the same geometry.

ST_Intersects
(Geometry, Geometry) → boolean Returns
true
if the given geometries spatially intersect in two dimensions (share any portion of space) andfalse
if they do not (they are disjoint).

ST_Overlaps
(Geometry, Geometry) → boolean Returns
true
if the given geometries share space, are of the same dimension, but are not completely contained by each other.

ST_Relate
(Geometry, Geometry) → boolean Returns
true
if first geometry is spatially related to second geometry.

ST_Touches
(Geometry, Geometry) → boolean Returns
true
if the given geometries have at least one point in common, but their interiors do not intersect.

ST_Within
(Geometry, Geometry) → boolean Returns
true
if first geometry is completely inside second geometry.
Operations

geometry_union
(array(Geometry)) → Geometry Returns a geometry that represents the point set union of the input geometries. Performance of this function, in conjunction with
array_agg()
to first aggregate the input geometries, may be better thangeometry_union_agg()
, at the expense of higher memory utilization.

ST_Boundary
(Geometry) → Geometry Returns the closure of the combinatorial boundary of this geometry.

ST_Buffer
(Geometry, distance) → Geometry Returns the geometry that represents all points whose distance from the specified geometry is less than or equal to the specified distance. If the points of the geometry are extremely close together (
delta < 1e8
), this might return an empty geometry.

ST_Difference
(Geometry, Geometry) → Geometry Returns the geometry value that represents the point set difference of the given geometries.

ST_Envelope
(Geometry) → Geometry Returns the bounding rectangular polygon of a geometry.

ST_EnvelopeAsPts
(Geometry) > array(Geometry) Returns an array of two points: the lower left and upper right corners of the bounding rectangular polygon of a geometry. Returns
null
if input geometry is empty.

expand_envelope
(Geometry, double) → Geometry Returns the bounding rectangular polygon of a geometry, expanded by a distance. Empty geometries will return an empty polygon. Negative or NaN distances will return an error. Positive infinity distances may lead to undefined results.

ST_ExteriorRing
(Geometry) → Geometry Returns a line string representing the exterior ring of the input polygon.

ST_Intersection
(Geometry, Geometry) → Geometry Returns the geometry value that represents the point set intersection of two geometries.

ST_SymDifference
(Geometry, Geometry) → Geometry Returns the geometry value that represents the point set symmetric difference of two geometries.

ST_Union
(Geometry, Geometry) → Geometry Returns a geometry that represents the point set union of the input geometries.
See also:
geometry_union()
,geometry_union_agg()
Accessors

ST_Area
(Geometry) → double Returns the 2D Euclidean area of a geometry.
For Point and LineString types, returns 0.0. For GeometryCollection types, returns the sum of the areas of the individual geometries.

ST_Area
(SphericalGeography) → double Returns the area of a polygon or multipolygon in square meters using a spherical model for Earth.

ST_Centroid
(Geometry) → Point Returns the point value that is the mathematical centroid of a geometry.

ST_ConvexHull
(Geometry) → Geometry Returns the minimum convex geometry that encloses all input geometries.

ST_CoordDim
(Geometry) → bigint Return the coordinate dimension of the geometry.

ST_Dimension
(Geometry) → bigint Returns the inherent dimension of this geometry object, which must be less than or equal to the coordinate dimension.

ST_Distance
(Geometry, Geometry) → double Returns the 2dimensional cartesian minimum distance (based on spatial ref) between two geometries in projected units.

ST_Distance
(SphericalGeography, SphericalGeography) → double Returns the greatcircle distance in meters between two SphericalGeography points.

ST_GeometryN
(Geometry, index) → Geometry Returns the geometry element at a given index (indices start at 1). If the geometry is a collection of geometries (e.g., GEOMETRYCOLLECTION or MULTI*), returns the geometry at a given index. If the given index is less than 1 or greater than the total number of elements in the collection, returns
NULL
. Use :func:ST_NumGeometries
to find out the total number of elements. Singular geometries (e.g., POINT, LINESTRING, POLYGON), are treated as collections of one element. Empty geometries are treated as empty collections.

ST_InteriorRingN
(Geometry, index) → Geometry Returns the interior ring element at the specified index (indices start at 1). If the given index is less than 1 or greater than the total number of interior rings in the input geometry, returns
NULL
. Throws an error if the input geometry is not a polygon. Use :func:ST_NumInteriorRing
to find out the total number of elements.

ST_GeometryType
(Geometry) → varchar Returns the type of the geometry.

ST_IsClosed
(Geometry) → boolean Returns
true
if the linestring’s start and end points are coincident.

ST_IsEmpty
(Geometry) → boolean Returns
true
if this Geometry is an empty geometrycollection, polygon, point etc.

ST_IsSimple
(Geometry) → boolean Returns
true
if this Geometry has no anomalous geometric points, such as self intersection or self tangency.

ST_IsRing
(Geometry) → boolean Returns
true
if and only if the line is closed and simple.

ST_IsValid
(Geometry) → boolean Returns
true
if and only if the input geometry is well formed. Usegeometry_invalid_reason()
to determine why the geometry is not well formed.

ST_Length
(Geometry) → double Returns the length of a linestring or multilinestring using Euclidean measurement on a two dimensional plane (based on spatial ref) in projected units.

ST_Length
(SphericalGeography) → double Returns the length of a linestring or multilinestring on a spherical model of the Earth. This is equivalent to the sum of greatcircle distances between adjacent points on the linestring.

ST_PointN
(LineString, index) → Point Returns the vertex of a linestring at a given index (indices start at 1). If the given index is less than 1 or greater than the total number of elements in the collection, returns
NULL
. Use :func:ST_NumPoints
to find out the total number of elements.

ST_Points
(Geometry) > array(Point) Returns an array of points in a linestring.

ST_XMax
(Geometry) → double Returns the X maximum of the geometry’s bounding box.

ST_YMax
(Geometry) → double Returns the Y maximum of the geometry’s bounding box.

ST_XMin
(Geometry) → double Returns the X minimum of the geometry’s bounding box.

ST_YMin
(Geometry) → double Returns the Y minimum of the geometry’s bounding box.

ST_StartPoint
(Geometry) → point Returns the first point of a LineString geometry as a Point. This is a shortcut for
ST_PointN(geometry, 1)
.

ST_EndPoint
(Geometry) → point Returns the last point of a LineString geometry as a Point. This is a shortcut for
ST_PointN(geometry, ST_NumPoints(geometry))
.

ST_X
(Point) → double Return the X coordinate of the point.

ST_Y
(Point) → double Return the Y coordinate of the point.

ST_InteriorRings
(Geometry) > array(Geometry) Returns an array of all interior rings found in the input geometry, or an empty array if the polygon has no interior rings. Returns
null
if the input geometry is empty. Throws an error if the input geometry is not a polygon.

ST_NumGeometries
(Geometry) → bigint Returns the number of geometries in the collection. If the geometry is a collection of geometries (e.g., GEOMETRYCOLLECTION or MULTI*), returns the number of geometries, for single geometries returns 1, for empty geometries returns 0. Note that empty geometries inside of a GEOMETRYCOLLECTION will count as a geometry; eg
ST_NumGeometries(ST_GeometryFromText('GEOMETRYCOLLECTION(MULTIPOINT EMPTY)'))
will evaluate to 1.

ST_Geometries
(Geometry) > array(Geometry) Returns an array of geometries in the specified collection. Returns a oneelement array if the input geometry is not a multigeometry. Returns
null
if input geometry is empty.

ST_NumPoints
(Geometry) → bigint Returns the number of points in a geometry. This is an extension to the SQL/MM
ST_NumPoints
function which only applies to point and linestring.

ST_NumInteriorRing
(Geometry) → bigint Returns the cardinality of the collection of interior rings of a polygon.

simplify_geometry
(Geometry, double) → Geometry Returns a “simplified” version of the input geometry using the DouglasPeucker algorithm. Will avoid creating derived geometries (polygons in particular) that are invalid.

line_locate_point
(LineString, Point) → double Returns a float between 0 and 1 representing the location of the closest point on the LineString to the given Point, as a fraction of total 2d line length.
Returns
null
if a LineString or a Point is empty ornull
.

line_interpolate_point
(LineString, double) → Geometry Returns the Point on the LineString at a fractional distance given by the double argument. Throws an exception if the distance is not between 0 and 1.
Returns an empty Point if the LineString is empty. Returns
null
if either the LineString or double is null.

geometry_invalid_reason
(Geometry) → varchar Returns the reason for why the input geometry is not valid. Returns
null
if the input is valid.

great_circle_distance
(latitude1, longitude1, latitude2, longitude2) → double Returns the greatcircle distance between two points on Earth’s surface in kilometers.
Aggregations

convex_hull_agg
(Geometry) → Geometry Returns the minimum convex geometry that encloses all input geometries.

geometry_union_agg
(Geometry) → Geometry Returns a geometry that represents the point set union of all input geometries.
Bing Tiles
These functions convert between geometries and
Bing tiles. For
Bing tiles, x
and y
refer to tile_x
and tile_y
.

bing_tile
(x, y, zoom_level) → BingTile Creates a Bing tile object from XY coordinates and a zoom level. Zoom levels from 1 to 23 are supported.

bing_tile
(quadKey) → BingTile Creates a Bing tile object from a quadkey.

bing_tile_at
(latitude, longitude, zoom_level) → BingTile Returns a Bing tile at a given zoom level containing a point at a given latitude and longitude. Latitude must be within
[85.05112878, 85.05112878]
range. Longitude must be within[180, 180]
range. Zoom levels from 1 to 23 are supported.

bing_tiles_around
(latitude, longitude, zoom_level) > array(BingTile) Returns a collection of Bing tiles that surround the point specified by the latitude and longitude arguments at a given zoom level.

bing_tiles_around
(latitude, longitude, zoom_level, radius_in_km) > array(BingTile) Returns a minimum set of Bing tiles at specified zoom level that cover a circle of specified radius in km around a specified (latitude, longitude) point.

bing_tile_coordinates
(tile) → row<x, y> Returns the XY coordinates of a given Bing tile.

bing_tile_polygon
(tile) → Geometry Returns the polygon representation of a given Bing tile.

bing_tile_quadkey
(tile) → varchar Returns the quadkey of a given Bing tile.

bing_tile_zoom_level
(tile) → tinyint Returns the zoom level of a given Bing tile.

geometry_to_bing_tiles
(geometry, zoom_level) > array(BingTile) Returns the minimum set of Bing tiles that fully covers a given geometry at a given zoom level. Zoom levels from 1 to 23 are supported.