ST_GeographyFromText

Converts a Well-Known Text (WKT) string into its corresponding GEOGRAPHY object. Use this function to convert a WKT string into the format expected by the Vertica Place functions.

A GEOGRAPHY object is a spatial object with coordinates (longitude, latitude) defined on the surface of the earth. Coordinates are expressed in degrees (longitude, latitude) from reference planes dividing the earth.

The maximum size of a GEOGRAPHY object is 10 MB. If you pass a WKT to ST_GeographyFromText, the result is a spatial object whose size is greater than 10 MB, ST_GeographyFromText returns an error.

The Open Geospatial Consortium (OGC) defines the format of a WKT string in Section 7 in the Simple Feature Access Part 1 - Common Architecture specification.

Behavior Type

Immutable

Syntax

ST_GeographyFromText( wkt [ USING PARAMETERS ignore_errors={'y'|'n'} ] )

Arguments

wkt

Well-Known Text (WKT) string of a GEOGRAPHY object, type LONG VARCHAR

ignore_errors

(Optional) ST_GeographyFromText returns the following, based on the parameters supplied:

  • NULL—If wkt is invalid and ignore_errors='y'.
  • Error—If wkt is invalid and ignore_errors='n' or is unspecified.

Returns

GEOGRAPHY

Supported Data Types

Data Type GEOGRAPHY (Perfect Sphere) GEOGRAPHY (WGS84)
Point Yes Yes
Multipoint

Yes

Yes

Linestring

Yes

Yes

Multilinestring

Yes

Yes

Polygon

Yes

Yes

Multipolygon

Yes

Yes

GeometryCollection

No

No

Example

The following example shows how to use ST_GeographyFromText.

Convert WKT into a GEOGRAPHY object:

=> CREATE TABLE wkt_ex (g GEOGRAPHY);
 CREATE TABLE
=> INSERT INTO wkt_ex VALUES(ST_GeographyFromText('POLYGON((1 2,3 4,2 3,1 2))'));
 OUTPUT 
--------
      1
(1 row)