ST_AsText

Name

ST_AsText — Return the Well-Known Text (WKT) representation of the geometry/geography without SRID metadata.

Synopsis

text ST_AsText ( geometry g1 ) ;

text ST_AsText ( geometry g1 , integer maxdecimaldigits=15 ) ;

text ST_AsText ( geography g1 ) ;

text ST_AsText ( geography g1 , integer maxdecimaldigits=15 ) ;

Description

Returns the Well-Known Text representation of the geometry/geography. Optional argument may be used to reduce the maximum number of decimal digits after floating point used in output (defaults to 15).

[Note]

The WKT spec does not include the SRID. To get the SRID as part of the data, use the non-standard PostGIS ST_AsEWKT

[Warning]

WKT format does not maintain precision so to prevent floating truncation, use ST_AsBinary or ST_AsEWKB format for transport.

[Note]

ST_AsText is the reverse of ST_GeomFromText . Use ST_GeomFromText to convert to a postgis geometry from ST_AsText representation.

Availability: 1.5 - support for geography was introduced.

Enhanced: 2.5 - optional parameter precision introduced.

This method implements the OpenGIS Simple Features Implementation Specification for SQL 1.1. s2.1.1.1

This method implements the SQL/MM specification. SQL-MM 3: 5.1.25

This method supports Circular Strings and Curves

Examples

SELECT ST_AsText('01030000000100000005000000000000000000
000000000000000000000000000000000000000000000000
F03F000000000000F03F000000000000F03F000000000000F03
F000000000000000000000000000000000000000000000000');

		   st_astext
--------------------------------
 POLYGON((0 0,0 1,1 1,1 0,0 0))
(1 row)

Providing the precision is optional.

SELECT ST_AsText(GeomFromEWKT('SRID=4326;POINT(111.1111111 1.1111111)'))
          st_astext
------------------------------
 POINT(111.1111111 1.1111111)
(1 row)
SELECT ST_AsText(GeomFromEWKT('SRID=4326;POINT(111.1111111 1.1111111)'),2)
st_astext
--------------------
POINT(111.11 1.11)
(1 row)