ST_AsText - Amazon Redshift
SyntaxArgumentsReturn typeExamples

ST_AsText

ST_AsText returns the well-known text (WKT) representation of an input geometry or geography. For 3DZ, 3DM, and 4D geometries or geographies, ST_AsEWKT appends Z, M, or ZM to the WKT value for the geometry or geography type.

Syntax

ST_AsText(geo)
ST_AsText(geo, precision)

Arguments

geo

A value of data type GEOMETRY or GEOGRAPHY, or an expression that evaluates to a GEOMETRY or GEOGRAPHY type.

precision

A value of data type INTEGER. For geometries, the coordinates of geo are displayed using the specified precision 1–20. If precision is not specified, the default is 15. For geogpraphies, the coordinates of geo are displayed using the specified precision. If precision is not specified, the default is 15.

Return type

VARCHAR

If geo is null, then null is returned.

If precision is null, then null is returned.

If the result is larger than a 64-KB VARCHAR, then an error is returned.

Examples

The following SQL returns the WKT representation of a linestring. 

SELECT ST_AsText(ST_GeomFromText('LINESTRING(3.141592653589793 -6.283185307179586,2.718281828459045 -1.414213562373095)', 4326));

st_astext
--------------------------------
LINESTRING(3.14159265358979 -6.28318530717959,2.71828182845905 -1.41421356237309)

The following SQL returns the WKT representation of a linestring. The coordinates of the geometries are displayed with six digits of precision. 

SELECT ST_AsText(ST_GeomFromText('LINESTRING(3.141592653589793 -6.283185307179586,2.718281828459045 -1.414213562373095)', 4326), 6);

st_astext
----------------------------------------------
 LINESTRING(3.14159 -6.28319,2.71828 -1.41421)

The following SQL returns the WKT representation of a geography. 

SELECT ST_AsText(ST_GeogFromText('LINESTRING(110 40, 2 3, -10 80, -7 9)'));

             st_astext
------------------------------------
 LINESTRING(110 40,2 3,-10 80,-7 9)