Geospatial/Geometry Functions
Tip
 Use ST_ISVALID to determine if a geometry object is valid. The functions below work best with valid geometry objects.
 Use the REMOVE_NULLABLE function to remove any nullable column types that could result from calculating a derived column (e.g., as in Projections) using one of the functions below.
Enhanced Performance Scalar Functions
The functions below all compare x and y coordinates to geometry objects (or vice versa), thus increasing their performance in queries. Each of these functions have a geometrytogeometry version listed in the next section.
Function  Description 

STXY_CONTAINS(geom, x, y)  Returns 1 (true) if geom contains the x and y coordinate, e.g. lies in the interior of geom. The coordinate cannot be on the boundary and also be contained because geom does not contain its boundary 
STXY_CONTAINSPROPERLY(geom, x, y)  Returns 1 (true) if the x and y coordinate intersects the interior of geom but not the boundary (or exterior) because geom does not contain its boundary but does contain itself 
STXY_COVEREDBY(x, y, geom)  Returns 1 (true) if the x and y coordinate is covered by geom 
STXY_COVERS(geom, x, y)  Returns 1 (true) if geom covers the x and y coordinate 
STXY_DISJOINT(x, y, geom)  Returns 1 (true) if the given x and y coordinate and the geometry geom do not spatially intersect. 
STXY_DISTANCE(x, y, geom[, solution])  Calculates the minimum distance between the given x and y coordinate and geom using the specified solution type. Solution types available:
Note: If the x and y coordinate and geom intersect (verify using ST_INTERSECTS), the distance will always be 0. 
STXY_DWITHIN(x, y, geom, distance[, solution])  Returns 1 (true) if the x and y coordinate is within the specified distance from geom using the specified solution type. Solution types available:

STXY_ENVDWITHIN(x, y, geom, distance[, solution])  Returns 1 (true) if the x and y coordinate is within the specified distance from the bounding box of geom using the specified solution type. Solution types available:

STXY_ENVINTERSECTS(x, y, geom)  Returns 1 (true) if the bounding box of the given geometry geom intersects the x and y coordinate. 
STXY_INTERSECTION(x, y, geom)  Returns the shared portion between the x and y coordinate and the given geometry geom, i.e. the point itself. 
STXY_INTERSECTS(x, y, geom)  Returns 1 (true) if the x and y coordinate and geom intersect in 2D. 
STXY_TOUCHES(x, y, geom)  Returns 1 (true) if the x and y coordinate and geometry geom have at least one point in common but their interiors do not intersect. If geom is a GEOMETRYCOLLECTION, a 0 is returned regardless if the point and geometry touch 
STXY_WITHIN(x, y, geom)  Returns 1 (true) if the x and y coordinate is completely inside the geom geometry i.e., not on the boundary 
Scalar Functions
Function  Description 

DIST(x1, y1, x2, y2)  Computes the Euclidean distance (in degrees), i.e. SQRT( (x1x2)*(x1x2) + (y1y2)*(y1y2) ). 
GEODIST(lon1, lat1, lon2, lat2)  Computes the geographic greatcircle distance (in meters) between two lat/lon points. 
GEOHASH_DECODE_LATITUDE(geohash)  Decodes a given geohash and returns the latitude value for the given hash string. Supports a maximum geohash character length of 16. 
GEOHASH_DECODE_LONGITUDE(geohash)  Decodes a given geohash and returns the longitude value for the given hash string. Supports a maximum geohash character length of 16. 
GEOHASH_ENCODE(lat, lon, precision)  Encodes a given coordinate pair and returns a hash string with a given precision. 
ST_ADDPOINT(linestring, point, position)  Adds a given point geometry to the given linestring geometry at the specified position, which is a 0based index. 
ST_ALMOSTEQUALS(geom1, geom2, decimal)  Returns 1 (true) if given geometries, geom1 and geom2, are almost spatially equal within the given amount of decimal scale. Note that geometries will still be considered equal if the decimal scale for the geometries is within a half order of magnitude of each other, e.g, if decimal is set to 2, then POINT(63.4 123.45) and POINT(63.4 123.454) are equal, but POINT(63.4 123.45) and POINT(63.4 123.459) are not equal. The geometry types must match to be considered equal. 
ST_AREA(geom[, solution])  Returns the area of the given geometry geom if it is a POLYGON or MULTIPOLYGON using the specified solution type. Returns 0 if the input geometry type is (MULTI)POINT or (MULTI)LINESTRING. Solution types available:

ST_AZIMUTH(geom1, geom2)  Returns the azimuth in radians defined by the segment between two POINTs, geom1 and geom2. Returns a null if the input geometry type is MULTIPOINT, (MULTI)LINESTRING, or (MULTI)POLYGON. 
ST_BOUNDARY(geom)  Returns the closure of the combinatorial boundary of a given geometry geom. Returns an empty geometry if geom is an empty geometry. Returns a null if geom is a GEOMETRYCOLLECTION 
ST_BOUNDINGDIAGONAL(geom)  Returns the diagonal of the given geometry's (geom) bounding box. 
ST_BUFFER(geom, radius[, style[, solution]])  Returns a geometry that represents all points whose distance from the given geometry geom is less than or equal to the given distance radius. The radius units can be specified by the solution type (default is in degrees) and the radius is created in the provided style. The style options are specified as a list of blankseparated keyvalue pairs, e.g., 'quad_segs=8 endcap=round'. If an empty style list ('') is provided, the default settings will be used. The style parameter must be specified to provide a solution type. Available style options:
Available solution types:
Tip To create a 5meter buffer around geom using the default styles: ST_BUFFER(geom, 5, '', 1). To create a 5foot (converting feet to meters) buffer around geom using the following styles: ST_BUFFER(geom, 5*0.3048,'quad_segs=4 endcap=flat', 1) 
ST_CENTROID(geom)  Calculates the center of the given geometry geom as a POINT. For (MULTI)POINTs, the center is calculated as the average of the input coordinates. For (MULTI)LINESTRINGs, the center is calculated as the weighted length of each given LINESTRING. For (MULTI)POLYGONs, the center is calculated as the weighted area of each given POLYGON. If geom is an empty geometry, an empty GEOMETRYCOLLECTION is returned 
ST_CLIP(geom1, geom2)  Returns the geometry shared between given geometries geom1 and geom2 
ST_CLOSESTPOINT(geom1, geom2[, solution])  Calculates the 2D POINT in geom1 that is closest to geom2 using the specified solution type. If geom1 or geom2 is empty, a null is returned. Solution types available:

ST_COLLECT(geom1, geom2)  Returns a MULTI* or GEOMETRYCOLLECTION comprising geom1 and geom2. If geom1 and geom2 are the same, singular geometry type, a MULTI* is returned, e.g., if geom1 and geom2 are both POINTs (empty or no), a MULTIPOINT is returned. If geom1 and geom2 are neither the same type nor singular geometries, a GEOMETRYCOLLECTION is returned. 
ST_COLLECTIONEXTRACT(collection, type)  Returns only the specified type from the given geometry collection. Type is a number that maps to the following:

ST_COLLECTIONHOMOGENIZE(collection)  Returns the simplest form of the given collection, e.g., a collection with a single POINT will be returned as POINT(x y), and a collection with multiple individual points will be returned as a MULTIPOINT. 
ST_CONCAVEHULL(geom, target_percent[, allow_holes])  Returns a potentially concave geometry that encloses all geometries found in the given geom set. Use target_percent (values between 0 and 1) to determine the percent of area of a convex hull the concave hull will attempt to fill; 1 will return the same geometry as an ST_CONVEXHULL operation. Set allow_holes to 1 (true) to allow holes in the resulting geometry; default value is 0 (false). Note that allow_holes is independent of the area of target_percent. 
ST_CONTAINS(geom1, geom2)  Returns 1 (true) if no points of geom2 lie in the exterior of geom1 and at least one point of geom2 lies in the interior of geom1. Note that geom1 does not contain its boundary but does contain itself. 
ST_CONTAINSPROPERLY(geom1, geom2)  Returns 1 (true) if geom2 intersects the interior of geom1 but not the boundary (or exterior). Note that geom1 does not contain its boundary but does contain itself. 
ST_CONVEXHULL(geom)  Returns the minimum convex geometry that encloses all geometries in the given geom set. 
ST_COORDDIM(geom)  Returns the coordinate dimension of the given geom, e.g., a geometry with x, y, and z coordinates would return 3. 
ST_COVEREDBY(geom1, geom2)  Returns 1 (true) if no point in geom1 is outside geom2. 
ST_COVERS(geom1, geom2)  Returns 1 (true) if no point in geom2 is outside geom1. 
ST_CROSSES(geom1, geom2)  Returns 1 (true) if the given geometries, geom1 and geom2, spatially cross, meaning some but not all interior points in common. If geom1 and/or geom2 are a GEOMETRYCOLLECTION, a 0 is returned regardless if the two geometries cross 
ST_DIFFERENCE(geom1, geom2)  Returns a geometry that represents the part of geom1 that does not intersect with geom2. 
ST_DIMENSION(geom)  Returns the dimension of the given geometry geom, which is less than or equal to the coordinate dimension. If geom is a single geometry, a 0 is for POINT, a 1 is for LINESTRING, and a 2 is for POLYGON. If geom is a collection, it will return the largest dimension from the collection. If geom is empty, 0 is returned. 
ST_DISJOINT(geom1, geom2)  Returns 1 (true) if the given geometries, geom1 and geom2, do not spatially intersect. 
ST_DISTANCE(geom1, geom2[, solution])  Calculates the minimum distance between the given geometries, geom1 and geom2, using the specified solution type. Solution types available:
Note: If geom1 and geom2 intersect (verify using ST_INTERSECTS), the distance will always be 0. 
ST_DISTANCEPOINTS(x1, y1, x2, y2[, solution])  Calculates the minimum distance between the given points, x1, y1 and x2, y2, using the specified solution type. Solution types available:

ST_DFULLYWITHIN(geom1, geom2, distance[, solution])  Returns 1 (true) if the maximum distance between geometries geom1 and geom2 is less than or equal to the specified distance of each other using the specified solution type. If geom1 or geom2 is null, 0 (false) is returned. Solution types available:

ST_DWITHIN(geom1, geom2, distance[, solution])  Returns 1 (true) if the minimum distance between geometries geom1 and geom2 is within the specified distance of each other using the specified solution type. Solution types available:

ST_ELLIPSE(centerx, centery, height, width)  Returns an ellipse using the following values:

ST_ENDPOINT(geom)  Returns the last point of the given geom as a POINT if it's a LINESTRING. If geom is not a a LINESTRING, null is returned. 
ST_ENVDWITHIN(geom1, geom2, distance[, solution])  Returns 1 (true) if geom1 is within the specified distance of the bounding box of geom2 using the specified solution type. Solution types available:

ST_ENVELOPE(geom)  Returns the bounding box of a given geometry geom. 
ST_ENVINTERSECTS(geom1, geom2)  Returns 1 (true) if the bounding box of the given geometries, geom1 and geom2, intersect. 
ST_EQUALS(geom1, geom2)  Returns 1 (true) if the given geometries, geom1 and geom2, are spatially equal. Note that order does not matter. 
ST_EQUALSEXACT(geom1, geom2, tolerance)  Returns 1 (true) if the given geometries, geom1 and geom2, are almost spatially equal within some given tolerance. If the values within the given geometries are within the tolerance value of each other, they're considered equal, e.g., if tolerance is 2, POINT(1 1) and POINT(1 3) are considered equal, but POINT(1 1) and POINT(1 3.1) are not. Note that the geometry types have to match for them to be considered equal. 
ST_ERASE(geom1, geom2)  Returns the result of erasing a portion of geom1 equal to the size of geom2. 
ST_EXPAND(geom, units)  Returns the bounding box expanded in all directions by the given units of the given geom. The expansion can also be defined for separate directions by providing separate parameters for each direction, e.g., ST_EXPAND(geom, unitsx, unitsy, unitsz, unitsm). 
ST_EXPANDBYRATE(geom, rate)  Returns the bounding box expanded by a given rate (a ratio of width and height) for the given geometry geom. The rate must be between 0 and 1. 
ST_EXTERIORRING(geom)  Returns a LINESTRING representing the exterior ring of the given POLYGON geom 
ST_FORCE2D(geom)  Returns the 2dimensional version (e.g., X and Y coordinates) of geom, the provided geometry or set of geometries (e.g., via GEOMETRYCOLLECTION or WKT column name). 
ST_FORCE3D(geom[, z])  Returns the 3dimensional version (e.g., X, Y, and Z coordinates) of geom, a provided geometry or set of geometries (e.g., via GEOMETRYCOLLECTION or WKT column name), using z as the geometry's new zvalue. The provided zvalues can also be derived from a numeric column. If no z is provided, a 0 will be applied. Note If a WKT column is provided for geom and a numeric column is provided for z, the z values will be matched to the provided geometries by row in the source table. If a singular geometry is provided for geom and a column is provided for z, threedimensional versions of the provided geometry will be returned for each z value found in the provided z column. If columns are provided for both geom and z and nulls are present in either column, the row containing null values will be skipped in the results. 
ST_GENERATEPOINTS(geom, num)  Creates a MULTIPOINT containing a number num of randomly generated points within the boundary of geom. 
ST_GEOHASH(geom, precision)  Returns a hash string representation of the given geometry geom with specified precision (the length of the geohash string). The longer the precision, the more precise the hash is. By default, precision is set to 20; the max for precision is 32. Returns null if geom is an empty geometry. Note The value returned will not be a geohash of the exact geometry but a geohash of the centroid of the given geometry 
ST_GEOMETRYN(geom, index)  Returns the index geometry back from the given geom geometry. The index starts from 1 to the number of geometry in geom. 
ST_GEOMETRYTYPE(geom)  Returns the type of geometry from the given geom. 
ST_GEOMETRYTYPEID(geom)  Returns the type ID of from geom. Type and ID mappings:

ST_GEOMFROMGEOHASH(geohash, precision)  Returns a POLYGON boundary box using the given geohash with a precision set by the integer precision. If precision is specified, the function will use as many characters in the hash equal to precision to create the geometry. If no precision is specified, the full length of the geohash is used. 
ST_GEOMFROMTEXT(wkt)  Returns a geometry from the given WellKnown text representation wkt. Note that this function is only compatible with constants 
ST_HEXGRID(xmin, ymin, xmax, ymax, cell_side[, limit])  Creates a MULTIPOLYGON containing a grid of hexagons between given minimum and maximum points of a bounding box. The minimum point cannot be greater than or equal to the maximum point. The size (in meters) of the individual hexagons' sides is determined by cell_side. The cell_side cannot be greater than the width or height of the bounding box. The maximum number of cells that can be produced is determined by limit, a positive integer. Supported values for limit:
If the custom limit request specifies more cells (based on the bounding box and the cell_side) than the system limit, a null is returned. 
ST_INTERIORRINGN(geom, n)  Returns the nth interior LINESTRING ring of the POLYGON geom. If geom is not a POLYGON or the given n is out of range, a null is returned. The index begins at 1 
ST_INTERSECTION(geom1, geom2)  Returns the shared portion between given geometries geom1 and geom2 
ST_INTERSECTS(geom1, geom2)  Returns 1 (true) if the given geometries, geom1 and geom2, intersect in 2D 
ST_ISCLOSED(geom)  Returns 1 (true) if the given geometry's (geom) start and end points coincide 
ST_ISCOLLECTION(geom)  Returns 1 (true) if geom is a collection, e.g., GEOMETRYCOLLECTION, MULTIPOINT, MULTILINESTRING, etc. 
ST_ISEMPTY(geom)  Returns 1 (true) if geom is empty 
ST_ISRING(geom)  Returns 1 (true) if LINESTRING geom is both closed (per ST_ISCLOSED) and "simple" (per ST_ISSIMPLE). Returns 0 if geom is not a LINESTRING 
ST_ISSIMPLE(geom)  Returns 1 (true) if geom has no anomalous geometric points, e.g., selfintersection or selftangency 
ST_ISVALID(geom)  Returns 1 (true) if geom (typically a [MULTI]POLYGON) is well formed. A POLYGON is valid if its rings do not cross and its boundary intersects only at POINTs (not along a line). The POLYGON must also not have dangling LINESTRINGs. A MULTIPOLYGON is valid if all of its elements are also valid and the interior rings of those elements do not intersect. Each element's boundaries may touch but only at POINTs (not along a line) 
ST_LENGTH(geom[, solution])  Returns the length of the geometry if it is a LINESTRING or MULTILINESTRING. Returns 0 if another type of geometry, e.g., POINT, MULTIPOINT, etc. GEOMETRYCOLLECTIONs are also supported but the aforementioned type limitation still applies; the collection will be recursively searched for LINESTRINGs and MULTILINESTRINGs and the summation of all supported geometry types is returned (unsupported types are ignored). Solution types available:

ST_LINEFROMMULTIPOINT(geom)  Creates a LINESTRING from geom if it is a MULTIPOINT. Returns null if geom is not a MULTIPOINT 
ST_LINEINTERPOLATEPOINT(geom, fraction)  Returns a POINT that represents the specified fraction of the LINESTRING geom. If geom is either empty or not a LINESTRING, null is returned 
ST_LINELOCATEPOINT(linestring, point)  Returns the location of the closest point in the given linestring to the given point as a value between 0 and 1. The return value is a fraction of the total linestring length. 
ST_LINEMERGE(geom)  Returns a LINESTRING or MULTILINESTRING from a given geom. If geom is a MULTILINESTRING comprising LINESTRINGs with shared endpoints, a contiguous LINESTRING is returned. If geom is a LINESTRING or a MULTILINESTRING comprising LINESTRINGS without shared endpoints, geom is returned If geom is an empty (MULTI)LINESTRING or a (MULTI)POINT or (MULTI)POLYGON, an empty GEOMETRYCOLLECTION is returned. 
ST_LINESUBSTRING(geom, start_fraction, end_fraction)  Returns the fraction of a given geom LINESTRING where start_fraction and end_fraction are between 0 and 1. For example, given LINESTRING(1 1, 2 2, 3 3) a start_fraction of 0 and an end_fraction of 0.25 would yield the first quarter of the given LINESTRING, or LINESTRING(1 1, 1.5 1.5). Returns null if start_fraction is greater than end_fraction. Returns null if input geometry is (MULTI)POINT, MULTILINESTRING, or (MULTI)POLYGON. Returns null if start_fraction and/or end_fraction are less than 0 or more than 1. 
ST_LONGESTLINE(geom1, geom2[, solution])  Returns the LINESTRING that represents the longest line of points between the two geometries. If multiple longest lines are found, only the first line found is returned. If geom1 or geom2 is empty, null is returned. Solution types available:

ST_MAKEENVELOPE(xmin, ymin, xmax, ymax)  Creates a rectangular POLYGON from the given min and max parameters 
ST_MAKELINE(geom[, geom2])  Creates a LINESTRING from geom if it is a MULTIPOINT. If geom is a POINT, there must be at least one other POINT to construct a LINESTRING. If geom is a LINESTRING, it must have at least two points. Returns null if geom is not a POINT, MULTIPOINT, or LINESTRING Note This function can be rather costly in terms of performance 
ST_MAKEPOINT(x, y)  Creates a POINT at the given coordinate Note This function can be rather costly in terms of performance 
ST_MAKEPOLYGON(geom)  Creates a POLYGON from geom. Inputs must be closed LINESTRINGs Note This function can be rather costly in terms of performance 
ST_MAKETRIANGLE2D(x1, y1, x2, y2, x3, y3)  Creates a closed 2D POLYGON with three vertices 
ST_MAKETRIANGLE3D(x1, y1, z1, x2, y2, z2, x3, y3, z3)  Creates a closed 3D POLYGON with three vertices 
ST_MAXDISTANCE(geom1, geom2[, solution])  Returns the maximum distance between the given geom1 and geom2 geometries using the specifed solution type. If geom1 or geom2 is empty, null is returned. Solution types available:

ST_MAXX(geom)  Returns the maximum x coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MAXY(geom)  Returns the maximum y coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MAXZ(geom)  Returns the maximum z coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MINX(geom)  Returns the minimum x coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MINY(geom)  Returns the minimum y coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MINZ(geom)  Returns the minimum z coordinate of a bounding box for the given geom geometry. This function works for 2D and 3D geometries. 
ST_MULTI(geom)  Returns geom as a MULTI geometry, e.g., a POINT would return a MULTIPOINT. 
ST_MULTIPLERINGBUFFERS(geom, distance, outside)  Creates multiple buffers at specified distance around the given geom geometry. Multiple distances are specified as commaseparated values in an array, e.g., [10,20,30]. Valid values for outside are:

ST_NEAR(geom1, geom2)  Returns the portion of geom2 that is closest to geom1. If geom2 is a singular geometry object (e.g., POINT, LINESTRING, POLYGON), geom2 will be returned. If geom2 a multigeometry, e.g., MULTIPOINT, MULTILINESTRING, etc., the nearest singular geometry in geom2 will be returned. 
ST_NORMALIZE(geom)  Returns geom in its normalized (canonical) form, which may rearrange the points in lexicographical order. 
ST_NPOINTS(geom)  Returns the number of points (vertices) in geom. 
ST_NUMGEOMETRIES(geom)  If geom is a collection or MULTI geometry, returns the number of geometries. If geom is a single geometry, returns 1. 
ST_NUMINTERIORRINGS(geom)  Returns the number of interior rings if geom is a POLYGON. Returns null if geom is anything else. 
ST_NUMPOINTS(geom)  Returns the number of points in the geom LINESTRING. Returns null if geom is not a LINESTRING. 
ST_OVERLAPS(geom1, geom2)  Returns 1 (true) if given geometries geom1 and geom2 share space. If geom1 and/or geom2 are a GEOMETRYCOLLECTION, a 0 is returned regardless if the two geometries overlap 
ST_PARTITION(geom, threshold)  Returns a MULTIPOLYGON representing the given geom partitioned into a number of POLYGONs with a maximum number of vertices equal to the given threshold. Minimum value for threshold is 10; default value is 10000. If geom is not a POLYGON or MULTIPOLYGON, geom is returned. If the number of vertices in geom is less than the threshold, geom is returned. 
ST_PERIMETER(geom[, solution])  Returns the perimeter of the geometry if it is a POLYGON or MULTIPOLYGON. Returns 0 if another type of geometry, e.g., POINT, MULTIPOINT, LINESTRING, or MULTILINESTRING. GEOMETRYCOLLECTIONs are also supported but the aforementioned type limitation still applies; the collection will be recursively searched for POLYGONs and MULTIPOLYGONs and the summation of all supported geometry types is returned (unsupported types are ignored). Solution types available:

ST_POINT(x, y)  Returns a POINT with the given x and y coordinates. 
ST_POINTFROMGEOHASH(geohash, precision)  Returns a POINT using the given geohash with a precision set by the integer precision. If precision is specified, the function will use as many characters in the hash equal to precision to create the geometry. If no precision is specified, the full length of the geohash is used. Note The POINT returned represents the center of the bounding box of the geohash 
ST_POINTGRID(xmin, ymin, xmax, ymax, cell_side[, limit])  Creates a MULTIPOLYGON containing a squareshaped grid of points between given minimum and maximum points of a bounding box. The minimum point cannot be greater than or equal to the maximum point. The distance between the points (in meters) is determined by cell_side. The cell_side cannot be greater than the width or height of the bounding box. The maximum number of cells that can be produced is determined by limit, a positive integer. Supported values for limit:
If the custom limit request specifies more cells (based on the bounding box and the cell_side) than the system limit, a null is returned. 
ST_POINTN(geom, n)  Returns the nth point in LINESTRING geom. Negative values are valid, but note that they are counted backwards from the end of geom. A null is returned if geom is not a LINESTRING. 
ST_POINTS(geom)  Returns a MULTIPOINT containing all of the coordinates of geom. 
ST_PROJECT(geom, distance, azimuth)  Returns a POINT projected from a start point geom along a geodesic calculated using distance and azimuth. If geom is not a POINT, null is returned. 
ST_REMOVEPOINT(geom, offset)  Remove a point from LINESTRING geom using offset to skip over POINTs in the LINESTRING. The offset is 0based. 
ST_REMOVEREPEATEDPOINTS(geom, tolerance)  Removes points from geom if the point's vertices are greater than or equal to the tolerance of the previous point in the geometry's list. If geom is not a MULTIPOINT, MULTILINESTRING, or a MULTIPOLYGON, no points will be removed. 
ST_REVERSE(geom)  Return the geometry with its coordinate order reversed. 
ST_SCALE(geom, x, y)  Scales geom by multiplying its respective vertices by the given x and y values. This function also supports scaling geom using another geometry object, e.g., ST_SCALE('POINT(3 4)', 'POINT(5 6)') would return POINT(15 24). If specifying x and y for scale, note that the default value is 0, e.g., ST_SCALE('POINT(1 3)', 4) would return POINT(4 0). 
ST_SEGMENTIZE(geom, max_segment_length[, solution])  Returns the given geom but segmentized n number of times depending on how the max_segment_length distance (in units based on the solution type) divides up the original geometry. The new geom is guaranteed to have segments that are smaller than the given max_segment_length. Note that POINTs are not able to be segmentized. Collection geometries (GEOMETRYCOLLECTION, MULTILINESTRING, MULTIPOINT, etc.) can be segmentized, but only the individual parts will be segmentized, not the collection as a whole. Solution types available:

ST_SETPOINT(geom1, position, geom2)  Replace a point of LINESTRING geom1 with POINT geom2 at position (base 0). Negative values are valid, but note that they are counted backwards from the end of geom. 
ST_SHAREDPATH(geom1, geom2)  Returns a collection containing paths shared by geom1 and geom2. 
ST_SHORTESTLINE(geom1, geom2)  Returns the 2D LINESTRING that represents the shortest line of points between the two geometries. If multiple shortest lines are found, only the first line found is returned. If geom1 or geom2 is empty, null is returned 
ST_SIMPLIFY(geom, tolerance)  Returns a simplified version of the given geom using an algorithm to reduce the number of points comprising a given geometry while attempting to best retain the original shape. The given tolerance determines how much to simplify the geometry. The higher the tolerance, the more simplified the returned geometry. Some holes might be removed and some invalid polygons (e.g., selfintersecting, etc.) might be present in the returned geometry. Only (MULTI)LINESTRINGs and (MULTI)POLYGONs can be simplified, including those found within GEOMETRYCOLLECTIONs; any other geometry objects will be returned unsimplified. Note The tolerance should be provided in the same units as the data. As a rule of thumb, a tolerance of 0.00001 would correspond to about one meter. 
ST_SIMPLIFYPRESERVETOPOLOGY(geom, tolerance)  Returns a simplified version of the given geom using an algorithm to reduce the number of points comprising a given geometry while attempting to best retain the original shape. The given tolerance determines how much to simplify the geometry. The higher the tolerance, the more simplified the returned geometry. No holes will be removed and no invalid polygons (e.g., selfintersecting, etc.) will be present in the returned geometry. Only (MULTI)LINESTRINGs and (MULTI)POLYGONs can be simplified, including those found within GEOMETRYCOLLECTIONs; any other geometry objects will be returned unsimplified. Note The tolerance should be provided in the same units as the data. As a rule of thumb, a tolerance of 0.00001 would correspond to about one meter. 
ST_SNAP(geom1, geom2, tolerance)  Snaps geom1 to geom2 within the given tolerance. If the tolerance causes geom1 to not snap, the geometries will be returned unchanged. 
ST_SPLIT(geom1, geom2)  Returns a collection of geometries resulting from the split between geom1 and geom2 geometries. 
ST_SQUAREGRID(xmin, ymin, xmax, ymax, cell_side[, limit])  Creates a MULTIPOLYGON containing a grid of squares between given minimum and maximum points of a bounding box. The minimum point cannot be greater than or equal to the maximum point. The size (in meters) of the individual squares' sides is determined by cell_side. The cell_side cannot be greater than the width or height of the bounding box. The maximum number of cells that can be produced is determined by limit, a positive integer. Supported values for limit:
If the custom limit request specifies more cells (based on the bounding box and the cell_side) than the system limit, a null is returned. 
ST_STARTPOINT(geom)  Returns the first point of LINESTRING geom as a POINT. Returns null if geom is not a LINESTRING. 
ST_SYMDIFFERENCE(geom1, geom2)  Returns a geometry that represents the portions of geom1 and geom2 geometries that do not intersect. 
ST_TOUCHES(geom1, geom2)  Returns 1 (true) if the given geometries, geom1 and geom2, have at least one point in common but their interiors do not intersect. If geom1 and/or geom2 are a GEOMETRYCOLLECTION, a 0 is returned regardless if the two geometries touch 
ST_TRANSLATE(geom, deltax, deltay[, deltaz])  Translate geom by given offsets deltax and deltay. A zcoordinate offset can be applied using deltaz. 
ST_TRIANGLEGRID(xmin, ymin, xmax, ymax, cell_side[, limit])  Creates a MULTIPOLYGON containing a grid of triangles between given minimum and maximum points of a bounding box. The minimum point cannot be greater than or equal to the maximum point. The size (in meters) of the individual triangles' sides is determined by cell_side. The cell_side cannot be greater than the width or height of the bounding box. The maximum number of cells that can be produced is determined by limit, a positive integer. Supported values for limit:
If the custom limit request specifies more cells (based on the bounding box and the cell_side) than the system limit, a null is returned. 
ST_UNION(geom1, geom2)  Returns a geometry that represents the point set union of the two given geometries, geom1 and geom2. 
ST_UNIONCOLLECTION(geom)  Returns a geometry that represents the point set union of a single given geometry geom. 
ST_UPDATE(geom1, geom2)  Returns a geometry that is geom1 geometry updated by geom2 geometry 
ST_VORONOIPOLYGONS(geom, tolerance)  Returns a GEOMETRYCOLLECTION containing Voronoi polygons (regions consisting of points closer to a vertex in geom than any other vertices in geom) calculated from the vertices in geom and the given tolerance. The tolerance determines the distance at which points will be considered the same. An empty GEOMETRYCOLLECTION is returned if geom is an empty geometry, a single POINT, or a LINESTRING or POLYGON composed of equivalent vertices (e.g., POLYGON((0 0, 0 0, 0 0, 0 0)), LINESTRING(0 0, 0 0)). 
ST_WITHIN(geom1, geom2)  Returns 1 (true) if the geom1 geometry is inside the geom2 geometry. Note that as long as at least one point is inside of geom2, geom1 is considered within geom2 even if the rest of the geom1 lies along the boundary of geom2 
ST_WKTTOWKB(geom)  Returns the binary form (WKB) of a geom (WKT) Note This function can only be used in queries against a single table. 
ST_X(geom)  Returns the X coordinate of the POINT geom; if the coordinate is not available, null is returned. geom must be a POINT. 
ST_XMAX(geom)  Alias for ST_MAXX() 
ST_XMIN(geom)  Alias for ST_MINX() 
ST_Y(geom)  Returns the Y coordinate of the POINT geom; if the coordinate is not available, null is returned. geom must be a POINT. 
ST_YMAX(geom)  Alias for ST_MAXY() 
ST_YMIN(geom)  Alias for ST_MINY() 
ST_ZMAX(geom)  Alias for ST_MAXZ() 
ST_ZMIN(geom)  Alias for ST_MINZ() 
Aggregation Functions
Function  Description 

ST_AGGREGATE_COLLECT(geom)  Alias for ST_COLLECT_AGGREGATE() 
ST_AGGREGATE_INTERSECTION(geom)  Alias for ST_INTERSECTION_AGGREGATE() 
ST_COLLECT_AGGREGATE(geom)  Returns a GEOMETRYCOLLECTION comprising all geometries found in the geom set. Any MULTI* geometries will be divided into separate singular geometries, e.g., MULTIPOINT((0 0), (1 1)) would be divided into POINT(0 0) and POINT(1 1) in the results; the same is true for elements of a GEOMETRYCOLLECTION found in geom, where a GEOMETRYCOLLECTION within the provided geom set will also be parsed, effectively flattening it and adding the individual geometries to the resulting GEOMETRYCOLLECTION. Any empty geometries in geom are ignored even if they are part of a GEOMETRYCOLLECTION. Any duplicate WKTs will be retained. 
ST_DISSOLVE(geom)  Dissolves all geometries within a given set into a single geometry. Note that the resulting single geometry can still be a group of noncontiguous geometries but represented as a single group, e.g., a GEOMETRYCOLLECTION. Best performance when used in conjunction with adjacent geometries 
ST_DISSOLVEOVERLAPPING(geom)  Dissolves all geometries within a given set into a single geometry. Note that the resulting single geometry can still be a group of noncontiguous geometries but represented as a single group, e.g., a GEOMETRYCOLLECTION. Best performance when used in conjunction with overlapping geometries 
ST_INTERSECTION_AGGREGATE(geom)  Returns a POLYGON or MULTIPOLYGON comprising the shared portion between all geometries found in the geom set. Returns an empty GEOMETRYCOLLECTION if there is no shared portion between all geometries. Functionally equivalent to ST_INTERSECTION(ST_INTERSECTION(ST_INTERSECTION(geom1, geom2), geom3), ... geomN). 
ST_LINESTRINGFROMORDEREDPOINTS(x, y, t)  Returns a LINESTRING that represents a "track" of the given points (x, y) ordered by the given sort column t (e.g., a timestamp or sequence number). If any of the values in the specified columns are null, the null "point" will be left out of the resulting LINESTRING. If there's only one nonnull "point" in the source table, a POINT is returned. If there are no nonnull "points" in the source table, a null is returned 
ST_LINESTRINGFROMORDEREDPOINTS3D(x, y, z, t)  Returns a LINESTRING that represents a "track" of the given 3D points (x, y, z) ordered by the given sort column t (e.g., a timestamp or sequence number). If any of the values in the specified columns are null, the null "point" will be left out of the resulting LINESTRING. If there's only one nonnull "point" in the source table, a POINT is returned. If there are no nonnull "points" in the source table, a null is returned 
ST_POLYGONIZE(geom)  Returns a GEOMETRYCOLLECTION containing POLYGONs comprising the provided (MULTI)LINESTRING(s). (MULTI)POINT and (MULTI)POLYGON geometries are ignored when calculating the resulting GEOMETRYCOLLECTION. If a valid POLYGON cannot be constructed from the provided (MULTI)LINESTRING(s), an empty GEOMETRYCOLLECTION will be returned. 