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Geospatial Function

Terakhir diperbarui: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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