ST_Buffer

Creates a GEOMETRY object greater than or equal to a specified distance from the boundary of a spatial object. The distance is measured in Cartesian coordinate units. ST_Buffer does not accept a distance size greater than +1e15 or less than –1e15.

Behavior type

Syntax

ST_Buffer( g, d )

Arguments

g

Spatial object for which you want to calculate the buffer, type GEOMETRY

d

Distance from the object in Cartesian coordinate units, type FLOAT

Returns

GEOMETRY

Supported data types

Usage tips

• If you specify a positive distance, ST_Buffer returns a polygon that represents the points within or equal to the distance outside the object. If you specify a negative distance, ST_Buffer returns a polygon that represents the points within or equal to the distance inside the object.

• For points, multipoints, linestrings, and multilinestrings, if you specify a negative distance, ST_Buffer returns an empty polygon.

• The Vertica Place version of ST_Buffer returns the buffer as a polygon, so the buffer object has corners at its vertices. It does not contain rounded corners.

Examples

The following example shows how to use ST_Buffer.

Returns a GEOMETRY object:

=> SELECT ST_AsText(ST_Buffer(ST_GeomFromText('POLYGON((0 1,1 4,4 3,0 1))'),1));
                                  ST_AsText
------------------------------------------------------------------------------
POLYGON ((-0.188847498856 -0.159920845081, -1.12155598386 0.649012935089, 0.290814745534 4.76344136152,
 0.814758063466 5.02541302048, 4.95372324225 3.68665254814, 5.04124517538 2.45512549204, -0.188847498856 -0.159920845081))
(1 row)