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Geometric data types represent two-dimensional spatial
objects. Table 8-16 shows the geometric
types available in PostgreSQL. The
most fundamental type, the point, forms the basis for all of the
other types.
Table 8-16. Geometric Types | Name | Storage Size | Representation | Description |
|---|
| point | 16 bytes | Point on the plane | (x,y) | | line | 32 bytes | Infinite line (not fully implemented) | ((x1,y1),(x2,y2)) | | 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 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 9.10.
Points are the fundamental two-dimensional building block for geometric types.
Values of type point are specified using the following syntax:
( x , y )
x , y
where x and y are the respective
coordinates as floating-point numbers.
Line segments (lseg) are represented by pairs of points.
Values of type lseg are specified using the following syntax:
( ( x1 , y1 ) , ( x2 , y2 ) )
( x1 , y1 ) , ( x2 , y2 )
x1 , y1 , x2 , y2
where
(x1,y1)
and
(x2,y2)
are the end points of the line segment.
Boxes are represented by pairs of points that are opposite
corners of the box.
Values of type box are specified using the following syntax:
( ( x1 , y1 ) , ( x2 , y2 ) )
( x1 , y1 ) , ( x2 , y2 )
x1 , y1 , x2 , y2
where
(x1,y1)
and
(x2,y2)
are any two opposite corners of the box.
Boxes are output using the first syntax.
The corners are reordered on input to store
the upper right corner, then the lower left corner.
Other corners of the box can be entered, but the lower
left and upper right corners are determined from the input and stored.
Paths are represented by lists of connected points. Paths can be
open, where
the first and last points in the list are not considered connected, or
closed,
where the first and last points are considered connected.
Values of type path are specified using the following syntax:
( ( 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.
Paths are output using the first syntax.
Polygons are represented by lists of points (the vertexes of the
polygon). Polygons should probably be
considered equivalent to closed paths, but are stored differently
and have their own set of support routines.
Values of type polygon are specified using the following syntax:
( ( 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.
Circles are represented by a center point and a radius.
Values of type circle are specified using the following syntax:
< ( x , y ) , r >
( ( x , y ) , r )
( x , y ) , r
x , y , r
where
(x,y)
is the center and r is the radius of the circle.
Circles are output using the first syntax.
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