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DocumentationCloud Log ServiceOperation GuideSearch and Analysis (Log Topic)Statistical Analysis (SQL)SQL FunctionsGeospatial Function
Geospatial Function
Last updated: 2024-03-20 11:47:49
This document introduces the basic syntax and examples of geospatial functions.
Concepts
Geospatial functions support Well-Known Text (WKT) and Well-Known Binary (WKB) forms of geometries. For related concepts, see Well-known text representation of geometry - Wikipedia.
Geometry | WKT Format |
Point | POINT (0 0) |
LineString | LINESTRING (0 0, 1 1, 1 2) |
Polygon | POLYGON ((0 0, 4 0, 4 4, 0 4, 0 0), (1 1, 2 1, 2 2, 1 2, 1 1)) |
MultiPoint | MULTIPOINT (0 0, 1 2) |
MultiLineString | MULTILINESTRING ((0 0, 1 1, 1 2), (2 3, 3 2, 5 4)) |
MultiPolygon | 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 | GEOMETRYCOLLECTION (POINT(2 3), LINESTRING (2 3, 3 4)) |
Geometries default to plane geometries, in which the shortest distance between two points is a straight line. Geometries also support spherical geometries, where the shortest distance between two points is a great circle arc. You can use
to_spherical_geography() to convert a plane geometry into a spherical geometry.
For example:
ST_Distance(ST_Point(-71.0882, 42.3607), ST_Point(-74.1197, 40.6976)) calculates the distance between two points on a plane, and the result is 3.4577.
ST_Distance(to_spherical_geography(ST_Point(-71.0882, 42.3607)), to_spherical_geography(ST_Point(-74.1197, 40.6976))) calculates the distance between two points on a sphere, and the result is 312822.179.When a length is calculated (for example,
ST_Distance() and ST_Length()), the unit is meter. When an area is calculated (for example, ST_Area()), the unit is square meter.Constructing a Geometry
Function | Return Value Type | Description |
ST_Point(double, double) | Point | Constructs a point. |
ST_LineFromText(varchar) | LineString | Constructs a LineString based on WKT text. |
ST_Polygon(varchar) | Polygon | Constructs a polygon based on WKT text. |
ST_GeometryFromText(varchar) | Geometry | Constructs a geometry based on WKT text. |
ST_GeomFromBinary(varbinary) | Geometry | Constructs a geometry based on WKB representation. |
ST_AsText(Geometry) | varchar | Converts a geometry into WKT format. |
to_spherical_geography(Geometry) | SphericalGeography | Converts a plane geometry into a spherical geometry. |
to_geometry(SphericalGeography) | Geometry | Converts a spherical geometry into a plane geometry. |
Relationship Tests
Function | Return Value Type | Description |
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. Returns false if the second geometry lies exactly on the boundary of the first geometry. |
ST_Crosses(Geometry, Geometry) | boolean | Returns true if the given geometries have some, but not all, interior points in common. |
ST_Disjoint(Geometry, Geometry) | boolean | Returns true if the given geometries do not spatially intersect. |
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. |
ST_Overlaps(Geometry, Geometry) | boolean | Returns true if the given geometries are of the same dimension, but are not completely contained by each other. |
ST_Relate(Geometry, Geometry) | boolean | Returns true if the first geometry is spatially related to the second geometry. |
ST_Touches(Geometry, Geometry) | boolean | Returns true if a geometry spatially touches another geometry, but their interiors do not intersect. |
ST_Within(Geometry, Geometry) | boolean | Returns true if first geometry is completely inside the second geometry. Return false if their boundaries intersect. |
Operations
Function | Return Value Type | Description |
geometry_nearest_points(Geometry, Geometry) | row(Point, Point) | Returns the two closest points between two geometries. |
geometry_union(array(Geometry)) | Geometry | Combines multiple geometries into one. |
ST_Boundary(Geometry) | Geometry | Returns the boundary (closure) of a geometry. |
ST_Buffer(Geometry, distance) | Geometry | Returns a geometric object that represents the union of all points whose distance from a geometry is less than or equal to a specified value. |
ST_Difference(Geometry, Geometry) | Geometry | Returns the geometry value that represents the point set difference of the two given geometries. |
ST_Envelope(Geometry) | Geometry | Returns the bounding rectangular polygon of the geometry. |
ST_ExteriorRing(Geometry) | Geometry | Returns the exterior ring of the input polygon. |
ST_Intersection(Geometry, Geometry) | Geometry | Returns the geometry value that represents the point set intersection of two given geometries. |
ST_SymDifference(Geometry, Geometry) | Geometry | Returns the geometry value that represents the point set symmetric difference of two geometries. |
Accessors
Function | Return Value Type | Description |
ST_Area(Geometry) | double | Returns the area of a polygon in a plane geometry. |
ST_Area(SphericalGeography) | double | Returns the area of a polygon in a spherical geometry. |
ST_Centroid(Geometry) | Geometry | Returns the point value that is the mathematical centroid of a geometry. |
ST_CoordDim(Geometry) | bigint | Returns the coordinate dimension of the geometry. |
ST_Dimension(Geometry) | bigint | Returns the inherent dimension of this geometry, which must be less than or equal to the coordinate dimension. |
ST_Distance(Geometry, Geometry) | double | Returns the minimum distance between two geometries. |
ST_Distance(SphericalGeography, SphericalGeography) | double | Returns the smallest distance between two spherical geographies. |
ST_IsClosed(Geometry) | boolean | Returns true if the start and end points of the given geometry are the same. |
ST_IsEmpty(Geometry) | boolean | Returns true if the geometry is an empty GeometryCollection, polygon, point etc. |
ST_IsRing(Geometry) | boolean | Returns true if and only if the geometry is a closed and simple line. |
ST_Length(Geometry) | double | Returns the length of a LineString or MultiLineString on a plane geometry. |
ST_Length(SphericalGeography) | double | Returns the length of a LineString or MultiLineString on a spherical geometry. |
ST_XMax(Geometry) | double | Returns the X maxima of a bounding box of a geometry. |
ST_YMax(Geometry) | double | Returns the Y maxima of a bounding box of a geometry. |
ST_XMin(Geometry) | double | Returns the X minima of a bounding box of a geometry. |
ST_YMin(Geometry) | double | Returns the Y minima of a bounding box of a geometry. |
ST_StartPoint(Geometry) | point | Returns the first point of a LineString geometry. |
ST_EndPoint(Geometry) | point | Returns the last point of a LineString geometry. |
ST_X(Point) | double | Returns the X coordinate of the point. |
ST_Y(Point) | double | Returns the Y coordinate of the point. |
ST_NumPoints(Geometry) | bigint | Returns the number of points in a geometry. |
ST_NumInteriorRing(Geometry) | bigint | Returns the number of the interior rings of a polygon. |
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