8.8. Geometric Types
Geometric data types represent twodimensional spatial objects. Table 8.20 shows the geometric types available in PostgreSQL .
Table 8.20. Geometric Types
Name  Storage Size  Description  Representation 

point

16 bytes  Point on a plane  (x,y) 
line

32 bytes  Infinite line  {A,B,C} 
lseg

32 bytes  Finite line segment  ((x1,y1),(x2,y2)) 
box

32 bytes  Rectangular box  ((x1,y1),(x2,y2)) 
path

16+16n bytes  Closed path (similar to polygon)  ((x1,y1),...) 
path

16+16n bytes  Open path  [(x1,y1),...] 
polygon

40+16n bytes  Polygon (similar to closed path)  ((x1,y1),...) 
circle

24 bytes  Circle  <(x,y),r> (center point and radius) 
A rich set of functions and operators is available to perform various geometric operations such as scaling, translation, rotation, and determining intersections. They are explained in Section 9.11 .
8.8.1. Points
Points are the fundamental twodimensional building block for geometric
types. Values of type
point
are specified using either of
the following syntaxes:
(x
,y
)x
,y
where
x
and
y
are the respective
coordinates, as floatingpoint numbers.
Points are output using the first syntax.
8.8.2. Lines
Lines are represented by the linear
equation
A
x +
B
y +
C
= 0,
where
A
and
B
are not both zero. Values
of type
line
are input and output in the following form:
{A
,B
,C
}
Alternatively, any of the following forms can be used for input:
[ (x1
,y1
) , (x2
,y2
) ] ( (x1
,y1
) , (x2
,y2
) ) (x1
,y1
) , (x2
,y2
)x1
,y1
,x2
,y2
where
(
and
x1
,
y1
)
(
are two different points on the line.
x2
,
y2
)
8.8.3. Line Segments
Line segments are represented by pairs of points that are the endpoints
of the segment. Values of type
lseg
are specified using any
of the following syntaxes:
[ (x1
,y1
) , (x2
,y2
) ] ( (x1
,y1
) , (x2
,y2
) ) (x1
,y1
) , (x2
,y2
)x1
,y1
,x2
,y2
where
(
and
x1
,
y1
)
(
are the end points of the line segment.
x2
,
y2
)
Line segments are output using the first syntax.
8.8.4. Boxes
Boxes are represented by pairs of points that are opposite
corners of the box.
Values of type
box
are specified using any of the following
syntaxes:
( (x1
,y1
) , (x2
,y2
) ) (x1
,y1
) , (x2
,y2
)x1
,y1
,x2
,y2
where
(
and
x1
,
y1
)
(
are any two opposite corners of the box.
x2
,
y2
)
Boxes are output using the second syntax.
Any two opposite corners can be supplied on input, but the values will be reordered as needed to store the upper right and lower left corners, in that order.
8.8.5. Paths
Paths are represented by lists of connected points. Paths can be open , where the first and last points in the list are considered not connected, or closed , where the first and last points are considered connected.
Values of type
path
are specified using any of the following
syntaxes:
[ (x1
,y1
) , ... , (xn
,yn
) ] ( (x1
,y1
) , ... , (xn
,yn
) ) (x1
,y1
) , ... , (xn
,yn
) (x1
,y1
, ... ,xn
,yn
)x1
,y1
, ... ,xn
,yn
where the points are the end points of the line segments
comprising the path. Square brackets (
[]
) indicate
an open path, while parentheses (
()
) indicate a
closed path. When the outermost parentheses are omitted, as
in the third through fifth syntaxes, a closed path is assumed.
Paths are output using the first or second syntax, as appropriate.
8.8.6. Polygons
Polygons are represented by lists of points (the vertexes of the polygon). Polygons are very similar to closed paths; the essential difference is that a polygon is considered to include the area within it, while a path is not.
Values of type
polygon
are specified using any of the
following syntaxes:
( (x1
,y1
) , ... , (xn
,yn
) ) (x1
,y1
) , ... , (xn
,yn
) (x1
,y1
, ... ,xn
,yn
)x1
,y1
, ... ,xn
,yn
where the points are the end points of the line segments comprising the boundary of the polygon.
Polygons are output using the first syntax.
8.8.7. Circles
Circles are represented by a center point and radius.
Values of type
circle
are specified using any of the
following syntaxes:
< (x
,y
) ,r
> ( (x
,y
) ,r
) (x
,y
) ,r
x
,y
,r
where
(
is the center point and
x
,
y
)
r
is the radius of the
circle.
Circles are output using the first syntax.