Chapter 8. PostGIS Reference

Table of Contents
8.1. PostGIS Geometry/Geography/Box Data Types
8.2. Table Management Functions
8.3. Geometry Constructors
8.4. Geometry Accessors
8.5. Geometry Editors
8.6. Spatial Reference System Functions
8.7. Affine Transformations
8.8. Geometry Outputs
8.9. Operators
8.10. Spatial Relationships
8.11. Measurement Functions
8.12. Geometry Processing
8.13. Clustering Functions
8.14. Bounding Box Functions
8.15. Linear Referencing
8.16. Trajectory Functions
8.17. SFCGAL Functions
8.18. Long Transaction Support
8.19. Version Functions
8.20. Grand Unified Custom Variables (GUCs)
8.21. Troubleshooting Functions

The functions given below are the ones which a user of PostGIS is likely to need. There are other functions which are required support functions to the PostGIS objects which are not of use to a general user.

[Note]

PostGIS has begun a transition from the existing naming convention to an SQL-MM-centric convention. As a result, most of the functions that you know and love have been renamed using the standard spatial type (ST) prefix. Previous functions are still available, though are not listed in this document where updated functions are equivalent. The non ST_ functions not listed in this documentation are deprecated and will be removed in a future release so STOP USING THEM.

8.1. PostGIS Geometry/Geography/Box Data Types

Abstract

This section lists the custom PostgreSQL data types installed by PostGIS to represent spatial data.

Each data type describes its type casting behaviour. A type cast converts values of one data type into another type. PostgreSQL allows defining casting behavior for custom types, along with the functions used to convert type values. Casts can be defined as automatic. This allows PostgreSQL to automatically convert a function argument to a type supported by the function. Casts can also be specified explicitly, using the syntax CAST(myval As sometype) or myval::sometype. This allows avoiding an issue that can occur when using an overloaded function which does not support a given type (for example, one that accepts a box2d or a box3d, but not a geometry.) Since geometry has an automatic cast to both box types, this will produce an "ambiguous function" error. To prevent the error use an explicit cast to the desired box type.

All data types can be CAST to text, so these do not need to be specified explicitly.

box2d — A 2-dimensional bounding box. Often used to describe the 2D extent of a geometry or collection of geometries.
box3d — A 3-dimensional bounding box. Often used to describe the 3D extent of a geometry or collection of geometries.
geometry — The type representing spatial features with planar coordinate systems.
geometry_dump — A composite type used to describe the parts of complex geometry.
geography — The type representing spatial features with geodetic (ellipsoidal) coordinate systems.

8.2. Table Management Functions

Abstract

These functions assist in defining tables containing geometry columns.

AddGeometryColumn — Adds a geometry column to an existing table.
DropGeometryColumn — Removes a geometry column from a spatial table.
DropGeometryTable — Drops a table and all its references in geometry_columns.
Find_SRID — Returns the SRID defined for a geometry column.
Populate_Geometry_Columns — Ensures geometry columns are defined with type modifiers or have appropriate spatial constraints.
UpdateGeometrySRID — Updates the SRID of all features in a geometry column, and the table metadata.
ST_MemSize — Returns the amount of memory space a geometry takes.

8.3. Geometry Constructors

ST_BdPolyFromText — Construct a Polygon given an arbitrary collection of closed linestrings as a MultiLineString Well-Known text representation.
ST_BdMPolyFromText — Construct a MultiPolygon given an arbitrary collection of closed linestrings as a MultiLineString text representation Well-Known text representation.
ST_Box2dFromGeoHash — Return a BOX2D from a GeoHash string.
ST_GeogFromText — Return a specified geography value from Well-Known Text representation or extended (WKT).
ST_GeographyFromText — Return a specified geography value from Well-Known Text representation or extended (WKT).
ST_GeogFromWKB — Creates a geography instance from a Well-Known Binary geometry representation (WKB) or extended Well Known Binary (EWKB).
ST_GeomFromTWKB — Creates a geometry instance from a TWKB ("Tiny Well-Known Binary") geometry representation.
ST_GeomCollFromText — Makes a collection Geometry from collection WKT with the given SRID. If SRID is not given, it defaults to 0.
ST_GeomFromEWKB — Return a specified ST_Geometry value from Extended Well-Known Binary representation (EWKB).
ST_GeomFromEWKT — Return a specified ST_Geometry value from Extended Well-Known Text representation (EWKT).
ST_GeometryFromText — Return a specified ST_Geometry value from Well-Known Text representation (WKT). This is an alias name for ST_GeomFromText
ST_GeomFromGeoHash — Return a geometry from a GeoHash string.
ST_GeomFromGML — Takes as input GML representation of geometry and outputs a PostGIS geometry object
ST_GeomFromGeoJSON — Takes as input a geojson representation of a geometry and outputs a PostGIS geometry object
ST_GeomFromKML — Takes as input KML representation of geometry and outputs a PostGIS geometry object
ST_GMLToSQL — Return a specified ST_Geometry value from GML representation. This is an alias name for ST_GeomFromGML
ST_GeomFromText — Return a specified ST_Geometry value from Well-Known Text representation (WKT).
ST_GeomFromWKB — Creates a geometry instance from a Well-Known Binary geometry representation (WKB) and optional SRID.
ST_LineFromEncodedPolyline — Creates a LineString from an Encoded Polyline.
ST_LineFromMultiPoint — Creates a LineString from a MultiPoint geometry.
ST_LineFromText — Makes a Geometry from WKT representation with the given SRID. If SRID is not given, it defaults to 0.
ST_LineFromWKB — Makes a LINESTRING from WKB with the given SRID
ST_LinestringFromWKB — Makes a geometry from WKB with the given SRID.
ST_MakeLine — Creates a Linestring from point, multipoint, or line geometries.
ST_MakeEnvelope — Creates a rectangular Polygon formed from the given minimums and maximums. Input values must be in SRS specified by the SRID.
ST_MakePolygon — Creates a Polygon formed by the given shell. Input geometries must be closed LINESTRINGS.
ST_MakePoint — Creates a 2D, 3DZ or 4D point geometry.
ST_MakePointM — Creates a point geometry with an x y and m coordinate.
ST_MLineFromText — Return a specified ST_MultiLineString value from WKT representation.
ST_MPointFromText — Makes a Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.
ST_MPolyFromText — Makes a MultiPolygon Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.
ST_Point — Returns an ST_Point with the given coordinate values. OGC alias for ST_MakePoint.
ST_PointFromGeoHash — Return a point from a GeoHash string.
ST_PointFromText — Makes a point Geometry from WKT with the given SRID. If SRID is not given, it defaults to unknown.
ST_PointFromWKB — Makes a geometry from WKB with the given SRID
ST_Polygon — Returns a polygon built from the specified linestring and SRID.
ST_PolygonFromText — Makes a Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.
ST_WKBToSQL — Return a specified ST_Geometry value from Well-Known Binary representation (WKB). This is an alias name for ST_GeomFromWKB that takes no srid
ST_WKTToSQL — Return a specified ST_Geometry value from Well-Known Text representation (WKT). This is an alias name for ST_GeomFromText

8.4. Geometry Accessors

GeometryType — Returns the type of the geometry as a string. Eg: 'LINESTRING', 'POLYGON', 'MULTIPOINT', etc.
ST_Boundary — Returns the closure of the combinatorial boundary of this Geometry.
ST_CoordDim — Return the coordinate dimension of the ST_Geometry value.
ST_Dimension — The inherent dimension of this Geometry object, which must be less than or equal to the coordinate dimension.
ST_EndPoint — Returns the last point of a LINESTRING or CIRCULARLINESTRING geometry as a POINT.
ST_Envelope — Returns a geometry representing the double precision (float8) bounding box of the supplied geometry.
ST_BoundingDiagonal — Returns the diagonal of the supplied geometry's bounding box.
ST_ExteriorRing — Returns a line string representing the exterior ring of the POLYGON geometry. Return NULL if the geometry is not a polygon. Will not work with MULTIPOLYGON
ST_GeometryN — Return the 1-based Nth geometry if the geometry is a GEOMETRYCOLLECTION, (MULTI)POINT, (MULTI)LINESTRING, MULTICURVE or (MULTI)POLYGON, POLYHEDRALSURFACE Otherwise, return NULL.
ST_GeometryType — Return the geometry type of the ST_Geometry value.
ST_HasArc — Returns true if a geometry or geometry collection contains a circular string
ST_InteriorRingN — Return the Nth interior linestring ring of the polygon geometry. Return NULL if the geometry is not a polygon or the given N is out of range.
ST_IsPolygonCCW — Returns true if all exterior rings are oriented counter-clockwise and all interior rings are oriented clockwise.
ST_IsPolygonCW — Returns true if all exterior rings are oriented clockwise and all interior rings are oriented counter-clockwise.
ST_IsClosed — Returns TRUE if the LINESTRING's start and end points are coincident. For Polyhedral surface is closed (volumetric).
ST_IsCollection — Returns TRUE if the argument is a collection (MULTI*, GEOMETRYCOLLECTION, ...)
ST_IsEmpty — Returns true if this Geometry is an empty geometrycollection, polygon, point etc.
ST_IsRing — Returns TRUE if this LINESTRING is both closed and simple.
ST_IsSimple — Returns (TRUE) if this Geometry has no anomalous geometric points, such as self intersection or self tangency.
ST_IsValid — Returns true if the ST_Geometry is well formed.
ST_IsValidReason — Returns text stating if a geometry is valid or not and if not valid, a reason why.
ST_IsValidDetail — Returns a valid_detail (valid,reason,location) row stating if a geometry is valid or not and if not valid, a reason why and a location where.
ST_M — Return the M coordinate of the point, or NULL if not available. Input must be a point.
ST_NDims — Returns coordinate dimension of the geometry as a small int. Values are: 2,3 or 4.
ST_NPoints — Return the number of points (vertexes) in a geometry.
ST_NRings — If the geometry is a polygon or multi-polygon returns the number of rings.
ST_NumGeometries — If geometry is a GEOMETRYCOLLECTION (or MULTI*) return the number of geometries, for single geometries will return 1, otherwise return NULL.
ST_NumInteriorRings — Return the number of interior rings of a polygon geometry.
ST_NumInteriorRing — Return the number of interior rings of a polygon in the geometry. Synonym for ST_NumInteriorRings.
ST_NumPatches — Return the number of faces on a Polyhedral Surface. Will return null for non-polyhedral geometries.
ST_NumPoints — Return the number of points in an ST_LineString or ST_CircularString value.
ST_PatchN — Return the 1-based Nth geometry (face) if the geometry is a POLYHEDRALSURFACE, POLYHEDRALSURFACEM. Otherwise, return NULL.
ST_PointN — Return the Nth point in the first LineString or circular LineString in the geometry. Negative values are counted backwards from the end of the LineString. Returns NULL if there is no linestring in the geometry.
ST_Points — Returns a MultiPoint containing all of the coordinates of a geometry.
ST_StartPoint — Returns the first point of a LINESTRING geometry as a POINT.
ST_Summary — Returns a text summary of the contents of the geometry.
ST_X — Return the X coordinate of the point, or NULL if not available. Input must be a point.
ST_Y — Return the Y coordinate of the point, or NULL if not available. Input must be a point.
ST_Z — Return the Z coordinate of the point, or NULL if not available. Input must be a point.
ST_Zmflag — Returns ZM (dimension semantic) flag of the geometries as a small int. Values are: 0=2d, 1=3dm, 2=3dz, 3=4d.

8.5. Geometry Editors

ST_AddPoint — Add a point to a LineString.
ST_CollectionExtract — Given a (multi)geometry, return a (multi)geometry consisting only of elements of the specified type.
ST_CollectionHomogenize — Given a geometry collection, return the "simplest" representation of the contents.
ST_Force2D — Force the geometries into a "2-dimensional mode".
ST_Force3D — Force the geometries into XYZ mode. This is an alias for ST_Force3DZ.
ST_Force3DZ — Force the geometries into XYZ mode.
ST_Force3DM — Force the geometries into XYM mode.
ST_Force4D — Force the geometries into XYZM mode.
ST_ForcePolygonCCW — Orients all exterior rings counter-clockwise and all interior rings clockwise.
ST_ForceCollection — Convert the geometry into a GEOMETRYCOLLECTION.
ST_ForcePolygonCW — Orients all exterior rings clockwise and all interior rings counter-clockwise.
ST_ForceSFS — Force the geometries to use SFS 1.1 geometry types only.
ST_ForceRHR — Force the orientation of the vertices in a polygon to follow the Right-Hand-Rule.
ST_ForceCurve — Upcast a geometry into its curved type, if applicable.
ST_LineMerge — Return a (set of) LineString(s) formed by sewing together a MULTILINESTRING.
ST_Multi — Return the geometry as a MULTI* geometry.
ST_Normalize — Return the geometry in its canonical form.
ST_QuantizeCoordinates — Sets least significant bits of coordinates to zero
ST_RemovePoint — Remove point from a linestring.
ST_Reverse — Return the geometry with vertex order reversed.
ST_Segmentize — Return a modified geometry/geography having no segment longer than the given distance.
ST_SetPoint — Replace point of a linestring with a given point.
ST_SnapToGrid — Snap all points of the input geometry to a regular grid.
ST_Snap — Snap segments and vertices of input geometry to vertices of a reference geometry.
ST_SwapOrdinates — Returns a version of the given geometry with given ordinate values swapped.

8.6. Spatial Reference System Functions

Abstract

These functions work with the Spatial Reference System of geometries.

ST_SetSRID — Set the SRID on a geometry to a particular integer value.
ST_SRID — Returns the spatial reference identifier for the ST_Geometry as defined in spatial_ref_sys table.
ST_Transform — Return a new geometry with its coordinates transformed to a different spatial reference system.

8.7. Affine Transformations

Abstract

These functions change the position and shape of geometries using affine transformations.

ST_Affine — Apply a 3D affine transformation to a geometry.
ST_Rotate — Rotates a geometry about an origin point.
ST_RotateX — Rotates a geometry about the X axis.
ST_RotateY — Rotates a geometry about the Y axis.
ST_RotateZ — Rotates a geometry about the Z axis.
ST_Scale — Scales a geometry by given factors.
ST_Translate — Translates a geometry by given offsets.
ST_TransScale — Translates and scales a geometry by given offsets and factors.

8.8. Geometry Outputs

ST_AsBinary — Return the Well-Known Binary (WKB) representation of the geometry/geography without SRID meta data.
ST_AsEncodedPolyline — Returns an Encoded Polyline from a LineString geometry.
ST_AsEWKB — Return the Well-Known Binary (WKB) representation of the geometry with SRID meta data.
ST_AsEWKT — Return the Well-Known Text (WKT) representation of the geometry with SRID meta data.
ST_AsGeoJSON — Return the geometry as a GeoJSON element.
ST_AsGML — Return the geometry as a GML version 2 or 3 element.
ST_AsHEXEWKB — Returns a Geometry in HEXEWKB format (as text) using either little-endian (NDR) or big-endian (XDR) encoding.
ST_AsKML — Return the geometry as a KML element. Several variants. Default version=2, default maxdecimaldigits=15
ST_AsLatLonText — Return the Degrees, Minutes, Seconds representation of the given point.
ST_AsSVG — Returns a Geometry in SVG path data given a geometry or geography object.
ST_AsText — Return the Well-Known Text (WKT) representation of the geometry/geography without SRID metadata.
ST_AsTWKB — Returns the geometry as TWKB, aka "Tiny Well-Known Binary"
ST_AsX3D — Returns a Geometry in X3D xml node element format: ISO-IEC-19776-1.2-X3DEncodings-XML
ST_GeoHash — Return a GeoHash representation of the geometry.
ST_AsGeobuf — Return a Geobuf representation of a set of rows.
ST_AsMVTGeom — Transform a geometry into the coordinate space of a Mapbox Vector Tile.
ST_AsMVT — Return a Mapbox Vector Tile representation of a set of rows.

8.9. Operators

&& — Returns TRUE if A's 2D bounding box intersects B's 2D bounding box.
&&(geometry,box2df) — Returns TRUE if a geometry's (cached) 2D bounding box intersects a 2D float precision bounding box (BOX2DF).
&&(box2df,geometry) — Returns TRUE if a 2D float precision bounding box (BOX2DF) intersects a geometry's (cached) 2D bounding box.
&&(box2df,box2df) — Returns TRUE if two 2D float precision bounding boxes (BOX2DF) intersect each other.
&&& — Returns TRUE if A's n-D bounding box intersects B's n-D bounding box.
&&&(geometry,gidx) — Returns TRUE if a geometry's (cached) n-D bounding box intersects a n-D float precision bounding box (GIDX).
&&&(gidx,geometry) — Returns TRUE if a n-D float precision bounding box (GIDX) intersects a geometry's (cached) n-D bounding box.
&&&(gidx,gidx) — Returns TRUE if two n-D float precision bounding boxes (GIDX) intersect each other.
&< — Returns TRUE if A's bounding box overlaps or is to the left of B's.
&<| — Returns TRUE if A's bounding box overlaps or is below B's.
&> — Returns TRUE if A' bounding box overlaps or is to the right of B's.
<< — Returns TRUE if A's bounding box is strictly to the left of B's.
<<| — Returns TRUE if A's bounding box is strictly below B's.
= — Returns TRUE if the coordinates and coordinate order geometry/geography A are the same as the coordinates and coordinate order of geometry/geography B.
>> — Returns TRUE if A's bounding box is strictly to the right of B's.
@ — Returns TRUE if A's bounding box is contained by B's.
@(geometry,box2df) — Returns TRUE if a geometry's 2D bounding box is contained into a 2D float precision bounding box (BOX2DF).
@(box2df,geometry) — Returns TRUE if a 2D float precision bounding box (BOX2DF) is contained into a geometry's 2D bounding box.
@(box2df,box2df) — Returns TRUE if a 2D float precision bounding box (BOX2DF) is contained into another 2D float precision bounding box.
|&> — Returns TRUE if A's bounding box overlaps or is above B's.
|>> — Returns TRUE if A's bounding box is strictly above B's.
~ — Returns TRUE if A's bounding box contains B's.
~(geometry,box2df) — Returns TRUE if a geometry's 2D bonding box contains a 2D float precision bounding box (GIDX).
~(box2df,geometry) — Returns TRUE if a 2D float precision bounding box (BOX2DF) contains a geometry's 2D bonding box.
~(box2df,box2df) — Returns TRUE if a 2D float precision bounding box (BOX2DF) contains another 2D float precision bounding box (BOX2DF).
~= — Returns TRUE if A's bounding box is the same as B's.
<-> — Returns the 2D distance between A and B.
|=| — Returns the distance between A and B trajectories at their closest point of approach.
<#> — Returns the 2D distance between A and B bounding boxes.
<<->> — Returns the n-D distance between the centroids of A and B bounding boxes.
<<#>> — Returns the n-D distance between A and B bounding boxes.

8.10. Spatial Relationships

Abstract

These functions determine spatial relationships between geometries.

ST_3DDWithin — For 3d (z) geometry type Returns true if two geometries 3d distance is within number of units.
ST_3DDFullyWithin — Returns true if all of the 3D geometries are within the specified distance of one another.
ST_3DIntersects — Returns TRUE if the Geometries "spatially intersect" in 3D - only for points, linestrings, polygons, polyhedral surface (area).
ST_Contains — Returns true if and only if no points of B lie in the exterior of A, and at least one point of the interior of B lies in the interior of A.
ST_ContainsProperly — Returns true if B intersects the interior of A but not the boundary (or exterior). A does not contain properly itself, but does contain itself.
ST_Covers — Returns 1 (TRUE) if no point in Geometry B is outside Geometry A
ST_CoveredBy — Returns 1 (TRUE) if no point in Geometry/Geography A is outside Geometry/Geography B
ST_Crosses — Returns TRUE if the supplied geometries have some, but not all, interior points in common.
ST_LineCrossingDirection — Given 2 linestrings, returns a number between -3 and 3 denoting what kind of crossing behavior. 0 is no crossing.
ST_Disjoint — Returns TRUE if the Geometries do not "spatially intersect" - if they do not share any space together.
ST_DFullyWithin — Returns true if all of the geometries are within the specified distance of one another
ST_DWithin — Returns true if the geometries are within the specified distance of one another. For geometry units are in those of spatial reference and for geography units are in meters and measurement is defaulted to use_spheroid=true (measure around spheroid), for faster check, use_spheroid=false to measure along sphere.
ST_Equals — Returns true if the given geometries represent the same geometry. Directionality is ignored.
ST_Intersects — Returns TRUE if the Geometries/Geography "spatially intersect in 2D" - (share any portion of space) and FALSE if they don't (they are Disjoint). For geography tolerance is 0.00001 meters (so any points that close are considered to intersect)
ST_OrderingEquals — Returns true if the given geometries represent the same geometry and points are in the same directional order.
ST_Overlaps — Returns TRUE if the Geometries share space, are of the same dimension, but are not completely contained by each other.
ST_PointInsideCircle — Is the point geometry inside the circle defined by center_x, center_y, radius
ST_Relate — Returns true if this Geometry is spatially related to anotherGeometry, by testing for intersections between the Interior, Boundary and Exterior of the two geometries as specified by the values in the intersectionMatrixPattern. If no intersectionMatrixPattern is passed in, then returns the maximum intersectionMatrixPattern that relates the 2 geometries.
ST_RelateMatch — Returns true if intersectionMattrixPattern1 implies intersectionMatrixPattern2
ST_Touches — Returns TRUE if the geometries have at least one point in common, but their interiors do not intersect.
ST_Within — Returns true if the geometry A is completely inside geometry B

8.11. Measurement Functions

Abstract

These functions compute measurements of distance, area and angles. There are also functions to compute geometry values determined by measurements.

ST_Area — Returns the area of a polygonal geometry.
ST_Azimuth — Returns the north-based azimuth as the angle in radians measured clockwise from the vertical on pointA to pointB.
ST_Angle — Returns the angle between 3 points, or between 2 vectors (4 points or 2 lines).
ST_ClosestPoint — Returns the 2D point on g1 that is closest to g2. This is the first point of the shortest line.
ST_3DClosestPoint — Returns the 3D point on g1 that is closest to g2. This is the first point of the 3D shortest line.
ST_Distance — Returns the distance between two geometry or geography values.
ST_3DDistance — Returns the 3D cartesian minimum distance (based on spatial ref) between two geometries in projected units.
ST_DistanceSphere — Returns minimum distance in meters between two lon/lat geometries using a spherical earth model.
ST_DistanceSpheroid — Returns the minimum distance between two lon/lat geometries using a spheroidal earth model.
ST_FrechetDistance — Returns the Fréchet distance between two geometries.
ST_HausdorffDistance — Returns the Hausdorff distance between two geometries.
ST_Length — Returns the 2D length of a linear geometry.
ST_Length2D — Returns the 2D length of a linear geometry. Alias for ST_Length
ST_3DLength — Returns the 3D length of a linear geometry.
ST_LengthSpheroid — Returns the 2D or 3D length/perimeter of a lon/lat geometry on a spheroid.
ST_LongestLine — Returns the 2D longest line between two geometries.
ST_3DLongestLine — Returns the 3D longest line between two geometries
ST_MaxDistance — Returns the 2D largest distance between two geometries in projected units.
ST_3DMaxDistance — Returns the 3D cartesian maximum distance (based on spatial ref) between two geometries in projected units.
ST_MinimumClearance — Returns the minimum clearance of a geometry, a measure of a geometry's robustness.
ST_MinimumClearanceLine — Returns the two-point LineString spanning a geometry's minimum clearance.
ST_Perimeter — Returns the length of the boundary of a polygonal geometry or geography.
ST_Perimeter2D — Returns the 2D perimeter of a polygonal geometry. Alias for ST_Perimeter.
ST_3DPerimeter — Returns the 3D perimeter of a polygonal geometry.
ST_Project — Returns a point projected from a start point by a distance and bearing (azimuth).
ST_ShortestLine — Returns the 2D shortest line between two geometries
ST_3DShortestLine — Returns the 3D shortest line between two geometries

8.12. Geometry Processing

ST_Buffer — (T) Returns a geometry covering all points within a given distance from the input geometry.
ST_BuildArea — Creates an areal geometry formed by the constituent linework of given geometry
ST_Centroid — Returns the geometric center of a geometry.
ST_ClipByBox2D — Returns the portion of a geometry falling within a rectangle.
ST_Collect — Return a specified ST_Geometry value from a collection of other geometries.
ST_ConcaveHull — The concave hull of a geometry represents a possibly concave geometry that encloses all geometries within the set. You can think of it as shrink wrapping.
ST_ConvexHull — The convex hull of a geometry represents the minimum convex geometry that encloses all geometries within the set.
ST_CurveToLine — Converts a CIRCULARSTRING/CURVEPOLYGON/MULTISURFACE to a LINESTRING/POLYGON/MULTIPOLYGON
ST_DelaunayTriangles — Return a Delaunay triangulation around the given input points.
ST_Difference — Returns a geometry that represents that part of geometry A that does not intersect with geometry B.
ST_Dump — Returns a set of geometry_dump (geom,path) rows, that make up a geometry g1.
ST_DumpPoints — Returns a set of geometry_dump (geom,path) rows of all points that make up a geometry.
ST_DumpRings — Returns a set of geometry_dump rows, representing the exterior and interior rings of a polygon.
ST_FlipCoordinates — Returns a version of the given geometry with X and Y axis flipped. Useful for people who have built latitude/longitude features and need to fix them.
ST_GeneratePoints — Converts a polygon or multi-polygon into a multi-point composed of randomly location points within the original areas.
ST_GeometricMedian — Returns the geometric median of a MultiPoint.
ST_Intersection — (T) Returns a geometry that represents the shared portion of geomA and geomB.
ST_LineToCurve — Converts a LINESTRING/POLYGON to a CIRCULARSTRING, CURVEPOLYGON
ST_MakeValid — Attempts to make an invalid geometry valid without losing vertices.
ST_MemUnion — Same as ST_Union, only memory-friendly (uses less memory and more processor time).
ST_MinimumBoundingCircle — Returns the smallest circle polygon that can fully contain a geometry. Default uses 48 segments per quarter circle.
ST_MinimumBoundingRadius — Returns the center point and radius of the smallest circle that can fully contain a geometry.
ST_OrientedEnvelope — Returns a minimum rotated rectangle enclosing a geometry.
ST_Polygonize — Aggregate. Creates a GeometryCollection containing possible polygons formed from the constituent linework of a set of geometries.
ST_Node — Node a set of linestrings.
ST_OffsetCurve — Return an offset line at a given distance and side from an input line. Useful for computing parallel lines about a center line
ST_PointOnSurface — Returns a POINT guaranteed to lie on the surface.
ST_RemoveRepeatedPoints — Returns a version of the given geometry with duplicated points removed.
ST_SharedPaths — Returns a collection containing paths shared by the two input linestrings/multilinestrings.
ST_ShiftLongitude — Toggle geometry coordinates between -180..180 and 0..360 ranges.
ST_WrapX — Wrap a geometry around an X value.
ST_Simplify — Returns a "simplified" version of the given geometry using the Douglas-Peucker algorithm.
ST_SimplifyPreserveTopology — Returns a "simplified" version of the given geometry using the Douglas-Peucker algorithm. Will avoid creating derived geometries (polygons in particular) that are invalid.
ST_SimplifyVW — Returns a "simplified" version of the given geometry using the Visvalingam-Whyatt algorithm
ST_ChaikinSmoothing — Returns a "smoothed" version of the given geometry using the Chaikin algorithm
ST_FilterByM — Filters vertex points based on their m-value
ST_SetEffectiveArea — Sets the effective area for each vertex, storing the value in the M ordinate. A simplified geometry can then be generated by filtering on the M ordinate.
ST_Split — Returns a collection of geometries resulting by splitting a geometry.
ST_SymDifference — Returns a geometry that represents the portions of A and B that do not intersect. It is called a symmetric difference because ST_SymDifference(A,B) = ST_SymDifference(B,A).
ST_Subdivide — Returns a set of geometry where no geometry in the set has more than the specified number of vertices.
ST_Union — Returns a geometry that represents the point set union of the Geometries.
ST_UnaryUnion — Like ST_Union, but working at the geometry component level.
ST_VoronoiLines — Returns the boundaries between the cells of the Voronoi diagram constructed from the vertices of a geometry.
ST_VoronoiPolygons — Returns the cells of the Voronoi diagram constructed from the vertices of a geometry.

8.13. Clustering Functions

Abstract

These functions implement clustering algorithms for sets of geometries.

ST_ClusterDBSCAN — Window function that returns a cluster id for each input geometry using the DBSCAN algorithm.
ST_ClusterIntersecting — Aggregate function that clusters the input geometries into connected sets.
ST_ClusterKMeans — Window function that returns a cluster id for each input geometry using the K-means algorithm.
ST_ClusterWithin — Aggregate function that clusters the input geometries by separation distance.

8.14. Bounding Box Functions

Abstract

These functions produce or operate on bounding boxes. They can also provide and accept geometry values, by using automatic or explicit casts.

See also Section 14.7, “PostGIS Box Functions”.

Box2D — Returns a BOX2D representing the 2D extent of the geometry.
Box3D — Returns a BOX3D representing the 3D extent of the geometry.
ST_EstimatedExtent — Return the 'estimated' extent of a spatial table.
ST_Expand — Returns a bounding box expanded from another bounding box or a geometry.
ST_Extent — an aggregate function that returns the bounding box that bounds rows of geometries.
ST_3DExtent — an aggregate function that returns the 3D bounding box that bounds rows of geometries.
ST_MakeBox2D — Creates a BOX2D defined by two 2D point geometries.
ST_3DMakeBox — Creates a BOX3D defined by two 3D point geometries.
ST_XMax — Returns the X maxima of a 2D or 3D bounding box or a geometry.
ST_XMin — Returns the X minima of a 2D or 3D bounding box or a geometry.
ST_YMax — Returns the Y maxima of a 2D or 3D bounding box or a geometry.
ST_YMin — Returns the Y minima of a 2D or 3D bounding box or a geometry.
ST_ZMax — Returns the Z maxima of a 2D or 3D bounding box or a geometry.
ST_ZMin — Returns the Z minima of a 2D or 3D bounding box or a geometry.

8.15. Linear Referencing

ST_LineInterpolatePoint — Returns a point interpolated along a line. Second argument is a float8 between 0 and 1 representing fraction of total length of linestring the point has to be located.
ST_3DLineInterpolatePoint — Returns a point interpolated along a line in 3D. Second argument is a float8 between 0 and 1 representing fraction of total length of linestring the point has to be located.
ST_LineInterpolatePoints — Returns one or more points interpolated along a line.
ST_LineLocatePoint — Returns a float between 0 and 1 representing the location of the closest point on LineString to the given Point, as a fraction of total 2d line length.
ST_LineSubstring — Return a linestring being a substring of the input one starting and ending at the given fractions of total 2d length. Second and third arguments are float8 values between 0 and 1.
ST_LocateAlong — Return a derived geometry collection value with elements that match the specified measure. Polygonal elements are not supported.
ST_LocateBetween — Return a derived geometry collection value with elements that match the specified range of measures inclusively.
ST_LocateBetweenElevations — Return a derived geometry (collection) value with elements that intersect the specified range of elevations inclusively.
ST_InterpolatePoint — Return the value of the measure dimension of a geometry at the point closed to the provided point.
ST_AddMeasure — Return a derived geometry with measure elements linearly interpolated between the start and end points.

8.16. Trajectory Functions

Abstract

These functions support working with trajectories. A trajectory is a linear geometry with a measure (M value) on each coordinate. The measure values must increase along the line. Spatio-temporal data can be modelled by using relative times (such as the epoch) as the measure values.

ST_IsValidTrajectory — Returns true if the geometry is a valid trajectory.
ST_ClosestPointOfApproach — Returns the measure at which points interpolated along two trajectories are closest.
ST_DistanceCPA — Returns the distance between the closest point of approach of two trajectories.
ST_CPAWithin — Returns true if the closest point of approach of two trajectories is within the specified distance.

8.17. SFCGAL Functions

Abstract

SFCGAL is a C++ wrapper library around CGAL that provides advanced 2D and 3D spatial functions. For robustness, geometry coordinates have an exact rational number representation.

Installation instructions for the library can be found on the SFCGAL home page (http://www.sfcgal.org). To enable the functions use create extension postgis_sfcgal.

postgis_sfcgal_version — Returns the version of SFCGAL in use
ST_Extrude — Extrude a surface to a related volume
ST_StraightSkeleton — Compute a straight skeleton from a geometry
ST_ApproximateMedialAxis — Compute the approximate medial axis of an areal geometry.
ST_IsPlanar — Check if a surface is or not planar
ST_Orientation — Determine surface orientation
ST_ForceLHR — Force LHR orientation
ST_MinkowskiSum — Performs Minkowski sum
ST_3DIntersection — Perform 3D intersection
ST_3DDifference — Perform 3D difference
ST_3DUnion — Perform 3D union
ST_3DArea — Computes area of 3D surface geometries. Will return 0 for solids.
ST_Tesselate — Perform surface Tesselation of a polygon or polyhedralsurface and returns as a TIN or collection of TINS
ST_Volume — Computes the volume of a 3D solid. If applied to surface (even closed) geometries will return 0.
ST_MakeSolid — Cast the geometry into a solid. No check is performed. To obtain a valid solid, the input geometry must be a closed Polyhedral Surface or a closed TIN.
ST_IsSolid — Test if the geometry is a solid. No validity check is performed.

8.18. Long Transaction Support

Abstract

These functions implement a row locking mechanism to support long transactions. They are provided primarily for implementors of the Web Feature Service specification.

AddAuth — Adds an authorization token to be used in the current transaction.
CheckAuth — Creates a trigger on a table to prevent/allow updates and deletes of rows based on authorization token.
DisableLongTransactions — Disables long transaction support.
EnableLongTransactions — Enables long transaction support.
LockRow — Sets lock/authorization for a row in a table.
UnlockRows — Removes all locks held by an authorization token.
[Note]

For the locking mechanism to operate correctly the serializable transaction isolation level must be used.

8.19. Version Functions

Abstract

These functions report and upgrade PostGIS versions.

PostGIS_Extensions_Upgrade — Packages and upgrades postgis extensions (e.g. postgis_raster, postgis_topology, postgis_sfcgal) to latest available version.
PostGIS_Full_Version — Reports full postgis version and build configuration infos.
PostGIS_GEOS_Version — Returns the version number of the GEOS library.
PostGIS_Liblwgeom_Version — Returns the version number of the liblwgeom library. This should match the version of PostGIS.
PostGIS_LibXML_Version — Returns the version number of the libxml2 library.
PostGIS_Lib_Build_Date — Returns build date of the PostGIS library.
PostGIS_Lib_Version — Returns the version number of the PostGIS library.
PostGIS_PROJ_Version — Returns the version number of the PROJ4 library.
PostGIS_Wagyu_Version — Returns the version number of the internal Wagyu library.
PostGIS_Scripts_Build_Date — Returns build date of the PostGIS scripts.
PostGIS_Scripts_Installed — Returns version of the postgis scripts installed in this database.
PostGIS_Scripts_Released — Returns the version number of the postgis.sql script released with the installed postgis lib.
PostGIS_Version — Returns PostGIS version number and compile-time options.

8.20. Grand Unified Custom Variables (GUCs)

Abstract

This section lists custom PostGIS Grand Unified Custom Variables (GUC). These can be set globally, by database, by session or by transaction. Best set at global or database level.

postgis.backend — The backend to service a function where GEOS and SFCGAL overlap. Options: geos or sfcgal. Defaults to geos.
postgis.gdal_datapath — A configuration option to assign the value of GDAL's GDAL_DATA option. If not set, the environmentally set GDAL_DATA variable is used.
postgis.gdal_enabled_drivers — A configuration option to set the enabled GDAL drivers in the PostGIS environment. Affects the GDAL configuration variable GDAL_SKIP.
postgis.enable_outdb_rasters — A boolean configuration option to enable access to out-db raster bands.

8.21. Troubleshooting Functions

Abstract

These functions are utilities for troubleshooting and repairing geometry data. They are only needed if the geometry data is corrupted in some way, which should never happen under normal circumstances.

PostGIS_AddBBox — Add bounding box to the geometry.
PostGIS_DropBBox — Drop the bounding box cache from the geometry.
PostGIS_HasBBox — Returns TRUE if the bbox of this geometry is cached, FALSE otherwise.