Chapter 5. PostGIS Reference
 5.1. PostGIS Geometry/Geography/Box Data Types
 5.2. Table Management Functions
 5.3. Geometry Constructors
 5.4. Geometry Accessors
 5.5. Geometry Editors
 5.6. Geometry Validation
 5.7. Spatial Reference System Functions
 5.8. Geometry Input
 5.9. Geometry Output
 5.10. Operators
 5.11. Spatial Relationships
 5.12. Measurement Functions
 5.13. Overlay Functions
 5.14. Geometry Processing
 5.15. Affine Transformations
 5.16. Clustering Functions
 5.17. Bounding Box Functions
 5.18. Linear Referencing
 5.19. Trajectory Functions
 5.20. SFCGAL Functions
 5.21. Long Transaction Support
 5.22. Version Functions
 5.23. Grand Unified Custom Variables (GUCs)
 5.24. 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.
PostGIS has begun a transition from the existing naming convention to an SQLMMcentric 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. 
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 have automatic behaviour, which allows automatic conversion of a function argument to a type supported by the function.
Some casts have
explicit
behaviour,
which means the cast must be specified using the syntax
CAST(myval As sometype)
or
myval::sometype
.
Explicit casting avoids the issue of ambiguous casts,
which can occur when using an overloaded function which does not support a given type.
For example, a function may accept a box2d or a box3d, but not a geometry.
Since geometry has an automatic cast to both box types, this produces 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 this does not need to be specified explicitly.
 box2d — A 2dimensional bounding box. Used to describe the 2D extent of a geometry or collection of geometries.
 box3d — A 3dimensional bounding box. 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.
 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_Collect — Creates a GeometryCollection or Multi* geometry from a set of geometries.
 ST_LineFromMultiPoint — Creates a LineString from a MultiPoint geometry.
 ST_MakeEnvelope — Creates a rectangular Polygon from minimum and maximum coordinates.
 ST_MakeLine — Creates a Linestring from Point, MultiPoint, or LineString geometries.
 ST_MakePoint — Creates a 2D, 3DZ or 4D Point.
 ST_MakePointM — Creates a Point from X, Y and M values.
 ST_MakePolygon — Creates a Polygon from a shell and optional list of holes.
 ST_Point — Creates a Point with the given coordinate values. Alias for ST_MakePoint.
 ST_Polygon — Creates a Polygon from a LineString with a specified SRID.
 ST_TileEnvelope Creates a rectangular Polygon in Web Mercator (SRID:3857) using the XYZ tile system.
 ST_HexagonGrid — Returns a set of hexagons and cell indices that completely cover the bounds of the geometry argument.
 ST_SquareGrid — Returns a set of grid squares and cell indices that completely cover the bounds of the geometry argument.
 ST_Hexagon — Returns a single hexagon, using the provided edge size and cell coordinate within the hexagon grid space.
 ST_Square — Returns a single square, using the provided edge size and cell coordinate within the hexagon grid space.
 GeometryType — Returns the type of a geometry as text.
 ST_Boundary — Returns the boundary of a geometry.
 ST_CoordDim — Return the coordinate dimension of a geometry.
 ST_Dimension — Returns the topological dimension of a geometry.

ST_Dump
— Returns a set of
geometry_dump
rows for the components of a geometry. 
ST_DumpPoints
— Returns a set of
geometry_dump
rows for the points in a geometry. 
ST_DumpRings
— Returns a set of
geometry_dump
rows for the exterior and interior rings of a Polygon.  ST_EndPoint — Returns the last point of a LineString or CircularLineString.
 ST_Envelope — Returns a geometry representing the bounding box of a geometry.
 ST_BoundingDiagonal — Returns the diagonal of a geometry's bounding box.
 ST_ExteriorRing — Returns a LineString representing the exterior ring of a Polygon.
 ST_GeometryN — Return the Nth geometry element of a geometry collection.
 ST_GeometryType — Returns the SQLMM type of a geometry as text.
 ST_HasArc — Tests if a geometry contains a circular arc
 ST_InteriorRingN — Returns the Nth interior ring (hole) of a Polygon.
 ST_IsPolygonCCW — Tests if Polygons have exterior rings oriented counterclockwise and interior rings oriented clockwise.
 ST_IsPolygonCW — Tests if Polygons have exterior rings oriented clockwise and interior rings oriented counterclockwise.
 ST_IsClosed — Tests if a LineStrings's start and end points are coincident. For a PolyhedralSurface tests if it is closed (volumetric).
 ST_IsCollection — Tests if a geometry is a geometry collection type.
 ST_IsEmpty — Tests if a geometry is empty.
 ST_IsRing — Tests if a LineString is closed and simple.
 ST_IsSimple — Tests if a geometry has no points of selfintersection or selftangency.
 ST_M — Returns the M coordinate of a Point.
 ST_MemSize — Returns the amount of memory space a geometry takes.
 ST_NDims — Returns the coordinate dimension of a geometry.
 ST_NPoints — Returns the number of points (vertices) in a geometry.
 ST_NRings — Returns the number of rings in a polygonal geometry.
 ST_NumGeometries — Returns the number of elements in a geometry collection.
 ST_NumInteriorRings — Returns the number of interior rings (holes) of a Polygon.
 ST_NumInteriorRing — Returns the number of interior rings (holes) of a Polygon. Aias for ST_NumInteriorRings
 ST_NumPatches — Return the number of faces on a Polyhedral Surface. Will return null for nonpolyhedral geometries.
 ST_NumPoints — Returns the number of points in a LineString or CircularString.
 ST_PatchN — Returns the Nth geometry (face) of a PolyhedralSurface.
 ST_PointN — Returns the Nth point in the first LineString or circular LineString in a geometry.
 ST_Points — Returns a MultiPoint containing all the coordinates of a geometry.
 ST_StartPoint — Returns the first point of a LineString.
 ST_Summary — Returns a text summary of the contents of a geometry.
 ST_X — Returns the X coordinate of a Point.
 ST_Y — Returns the Y coordinate of a Point.
 ST_Z — Returns the Z coordinate of a Point.
 ST_Zmflag — Returns a code indicating the ZM coordinate dimension of a geometry.
 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_CurveToLine — Converts a geometry containing curves to a linear geometry.
 ST_FlipCoordinates — Returns a version of a geometry with X and Y axis flipped.
 ST_Force2D — Force the geometries into a "2dimensional 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 counterclockwise and all interior rings clockwise.
 ST_ForceCollection — Convert the geometry into a GEOMETRYCOLLECTION.
 ST_ForcePolygonCW — Orients all exterior rings clockwise and all interior rings counterclockwise.
 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 RightHandRule.
 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_LineToCurve — Converts a linear geometry to a curved geometry.
 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_RemoveRepeatedPoints — Returns a version of the given geometry with duplicated points removed.
 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_ShiftLongitude — Shifts a geometry with geographic coordinates between 180..180 and 0..360.
 ST_WrapX — Wrap a geometry around an X value.
 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.
 ST_IsValid — Tests if a geometry is wellformed in 2D.

ST_IsValidDetail
— Returns a
valid_detail
row stating if a geometry is valid, and if not a reason why and a location.  ST_IsValidReason — Returns text stating if a geometry is valid, or a reason for invalidity.
 ST_MakeValid — Attempts to make an invalid geometry valid without losing vertices.
 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.
 ST_BdPolyFromText — Construct a Polygon given an arbitrary collection of closed linestrings as a MultiLineString WellKnown text representation.
 ST_BdMPolyFromText — Construct a MultiPolygon given an arbitrary collection of closed linestrings as a MultiLineString text representation WellKnown text representation.
 ST_GeogFromText — Return a specified geography value from WellKnown Text representation or extended (WKT).
 ST_GeographyFromText — Return a specified geography value from WellKnown Text representation or extended (WKT).
 ST_GeomCollFromText — Makes a collection Geometry from collection WKT with the given SRID. If SRID is not given, it defaults to 0.
 ST_GeomFromEWKT — Return a specified ST_Geometry value from Extended WellKnown Text representation (EWKT).
 ST_GeometryFromText — Return a specified ST_Geometry value from WellKnown Text representation (WKT). This is an alias name for ST_GeomFromText
 ST_GeomFromText — Return a specified ST_Geometry value from WellKnown Text representation (WKT).
 ST_LineFromText — Makes a Geometry from WKT representation with the given SRID. If SRID is not given, it defaults to 0.
 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_PointFromText — Makes a point Geometry from WKT with the given SRID. If SRID is not given, it defaults to unknown.
 ST_PolygonFromText — Makes a Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.
 ST_WKTToSQL — Return a specified ST_Geometry value from WellKnown Text representation (WKT). This is an alias name for ST_GeomFromText
 ST_GeogFromWKB — Creates a geography instance from a WellKnown Binary geometry representation (WKB) or extended Well Known Binary (EWKB).
 ST_GeomFromEWKB — Return a specified ST_Geometry value from Extended WellKnown Binary representation (EWKB).
 ST_GeomFromWKB — Creates a geometry instance from a WellKnown Binary geometry representation (WKB) and optional SRID.

ST_LineFromWKB
— Makes a
LINESTRING
from WKB with the given SRID  ST_LinestringFromWKB — Makes a geometry from WKB with the given SRID.
 ST_PointFromWKB — Makes a geometry from WKB with the given SRID
 ST_WKBToSQL — Return a specified ST_Geometry value from WellKnown Binary representation (WKB). This is an alias name for ST_GeomFromWKB that takes no srid
 ST_Box2dFromGeoHash — Return a BOX2D from a GeoHash string.
 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_GeomFromTWKB Creates a geometry instance from a TWKB ("Tiny WellKnown Binary") geometry representation.
 ST_GMLToSQL — Return a specified ST_Geometry value from GML representation. This is an alias name for ST_GeomFromGML
 ST_LineFromEncodedPolyline — Creates a LineString from an Encoded Polyline.
 ST_PointFromGeoHash — Return a point from a GeoHash string.
 ST_AsBinary — Return the WellKnown Binary (WKB) representation of the geometry/geography without SRID meta data.
 ST_AsEWKB — Return the WellKnown Binary (WKB) representation of the geometry with SRID meta data.
 ST_AsHEXEWKB — Returns a Geometry in HEXEWKB format (as text) using either littleendian (NDR) or bigendian (XDR) encoding.
 ST_AsEncodedPolyline — Returns an Encoded Polyline from a LineString geometry.
 ST_AsGeobuf — Return a Geobuf representation of a set of rows.
 ST_AsGeoJSON — Return the geometry as a GeoJSON element.
 ST_AsGML — Return the geometry as a GML version 2 or 3 element.
 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_AsMVTGeom Transform a geometry into the coordinate space of a Mapbox Vector Tile.
 ST_AsMVT — Aggregate function returning a Mapbox Vector Tile representation of a set of rows.
 ST_AsSVG — Returns SVG path data for a geometry.
 ST_AsTWKB — Returns the geometry as TWKB, aka "Tiny WellKnown Binary"
 ST_AsX3D — Returns a Geometry in X3D xml node element format: ISOIEC197761.2X3DEncodingsXML
 ST_GeoHash — Return a GeoHash representation of the geometry.

&&
— 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 nD bounding box intersects B's nD bounding box. 
&&&(geometry,gidx)
— Returns
TRUE
if a geometry's (cached) nD bounding box intersects a nD float precision bounding box (GIDX). 
&&&(gidx,geometry)
— Returns
TRUE
if a nD float precision bounding box (GIDX) intersects a geometry's (cached) nD bounding box. 
&&&(gidx,gidx)
— Returns
TRUE
if two nD 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 nD distance between the centroids of A and B bounding boxes.
 <<#>> — Returns the nD distance between A and B bounding boxes.
 ST_3DIntersects — Returns true if two 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 true if no point in B is outside A
 ST_CoveredBy — Returns true if no point in Geometry/Geography A is outside Geometry/Geography B
 ST_Crosses — Returns true if two geometries have some, but not all, interior points in common.
 ST_LineCrossingDirection — Returns a number indicating the crossing behavior of two LineStrings.
 ST_Disjoint — Returns true if two geometries do not spatially intersect (they have no point in common).
 ST_Equals — Returns true if two geometries include the same set of points in space.
 ST_Intersects — Returns true if two Geometries/Geography spatially intersect in 2D (have at least one point in common).
 ST_OrderingEquals — Returns true if two geometries represent the same geometry and have points in the same directional order.
 ST_Overlaps — Returns true if two geometries intersect and have the same dimension, but are not completely contained by each other.
 ST_Relate — Tests if two geometries have a topological relationship matching a given Intersection Matrix pattern, or computes their Intersection Matrix
 ST_RelateMatch — Tests if a DE9IM Intersection Matrix matches an Intersection Matrix pattern
 ST_Touches — Returns true if two geometries have at least one point in common, but their interiors do not intersect.
 ST_Within — Returns true if geometry A is completely inside geometry B
 ST_3DDWithin — Returns true if two 3D geometries are within a given 3D distance
 ST_3DDFullyWithin — Returns true if two 3D geometries are entirely within a given 3D distance
 ST_DFullyWithin — Returns true if two geometries are entirely within a given distance
 ST_DWithin — Returns true if two geometries are within a given distance
 ST_PointInsideCircle — Tests if a point geometry is inside a circle defined by a center and radius.
 ST_Area — Returns the area of a polygonal geometry.
 ST_Azimuth — Returns the northbased 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 twopoint 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
 ST_ClipByBox2D — Returns the portion of a geometry falling within a rectangle.
 ST_Difference — Returns a geometry representing the part of geometry A that does not intersect geometry B.
 ST_Intersection — Returns a geometry representing the shared portion of geometries A and B.
 ST_MemUnion — Aggregate function which unions geometry in a memoryefficent but slower way
 ST_Node — Nodes a collection of lines.
 ST_Split — Returns a collection of geometries created by splitting a geometry by another geometry.
 ST_Subdivide — Computes a rectilinear subdivision of a geometry.
 ST_SymDifference — Returns a geometry representing the portions of geometries A and B that do not intersect.
 ST_Union — Returns a geometry representing the pointset union of the input geometries.
 ST_UnaryUnion — Computes the union of the components of a single geometry.
 ST_Buffer — Returns a geometry covering all points within a given distance from a geometry.
 ST_BuildArea — Creates a polygonal geometry formed by the linework of a geometry.
 ST_Centroid — Returns the geometric center of a geometry.
 ST_ConcaveHull — Computes a possibly concave geometry that encloses all input geometry vertices
 ST_ConvexHull — Computes the convex hull of a geometry.
 ST_DelaunayTriangles — Returns the Delaunay triangulation of the vertices of a geometry.
 ST_FilterByM — Removes vertices based on their M value
 ST_GeneratePoints — Generates random points contained in a Polygon or MultiPolygon.
 ST_GeometricMedian — Returns the geometric median of a MultiPoint.
 ST_MaximumInscribedCircle — Computes the largest circle that is fully contained within a geometry.
 ST_MinimumBoundingCircle — Returns the smallest circle polygon that contains a geometry.
 ST_MinimumBoundingRadius — Returns the center point and radius of the smallest circle that contains a geometry.
 ST_OrientedEnvelope — Returns a minimumarea rectangle containing a geometry.
 ST_OffsetCurve — Returns an offset line at a given distance and side from an input line.
 ST_PointOnSurface — Returns a point guaranteed to lie in a polygon or on a geometry.
 ST_Polygonize — Computes a collection of polygons formed from the linework of a set of geometries.
 ST_ReducePrecision — Returns a valid geometry with all points rounded to the provided grid tolerance.
 ST_SharedPaths — Returns a collection containing paths shared by the two input linestrings/multilinestrings.
 ST_Simplify — Returns a simplified version of a geometry, using the DouglasPeucker algorithm.
 ST_SimplifyPreserveTopology — Returns a simplified and valid version of a geometry, using the DouglasPeucker algorithm.
 ST_SimplifyVW — Returns a simplified version of a geometry, using the VisvalingamWhyatt algorithm
 ST_ChaikinSmoothing — Returns a smoothed version of a geometry, using the Chaikin algorithm
 ST_SetEffectiveArea — Sets the effective area for each vertex, using the VisvalingamWhyatt algorithm.
 ST_VoronoiLines — Returns the boundaries of the Voronoi diagram of the vertices of a geometry.
 ST_VoronoiPolygons — Returns the cells of the Voronoi diagram of the vertices of a geometry.
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.
 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 Kmeans algorithm.
 ST_ClusterWithin — Aggregate function that clusters the input geometries by separation distance.
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 9.7, “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.
 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.
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. Spatiotemporal 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.
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_ConstrainedDelaunayTriangles — Return a constrained Delaunay triangulation around the given input geometry.
 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.
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.
For the locking mechanism to operate correctly the serializable transaction isolation level must be used. 
 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 compiletime options.
 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 outdb raster bands.
 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.