<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.249 2010/06/29 00:03:39 petere Exp $ -->

<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.250 2010/07/03 04:03:06 tgl Exp $ -->

<chapter id="datatype">

<title>Data Types</title>

<para>

A rich set of functions and operators is available to perform various geometric

operations such as scaling, translation, rotation, and determining

operations such as scaling, translation, rotation, and determining

intersections. They are explained in <xref linkend="functions-geometry">.

</para>

</indexterm>

<para>

Points are the fundamental two-dimensional building block for geometric types.

Values of type <type>point</type> are specified using the following syntax:

Points are the fundamental two-dimensional building block for geometric

types. Values of type <type>point</type> are specified using either of

the following syntaxes:

<synopsis>

( <replaceable>x</replaceable> , <replaceable>y</replaceable> )

where <replaceable>x</> and <replaceable>y</> are the respective

coordinates, as floating-point numbers.

</para>

<para>

Points are output using the first syntax.

</para>

</sect2>

<sect2>

<para>

Line segments (<type>lseg</type>) are represented by pairs of points.

Values of type <type>lseg</type> are specified using the following syntax:

Values of type <type>lseg</type> are specified using any of the following

syntaxes:

<synopsis>

[ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) ]

( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , <replaceable>x2</replaceable> , <replaceable>y2</replaceable>

</synopsis>

<literal>(<replaceable>x2</replaceable>,<replaceable>y2</replaceable>)</literal>

are the end points of the line segment.

</para>

<para>

Line segments are output using the first syntax.

</para>

</sect2>

<sect2>

<para>

Boxes are represented by pairs of points that are opposite

corners of the box.

Values of type <type>box</type> are specified using the following syntax:

Values of type <type>box</type> are specified using any of the following

syntaxes:

<synopsis>

( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , <replaceable>x2</replaceable> , <replaceable>y2</replaceable>

</synopsis>

</para>

<para>

Boxes are output using the first syntax.

Boxes are output using the second syntax.

</para>

<para>

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.

upper right and lower left corners, in that order.

</para>

</sect2>

</para>

<para>

Values of type <type>path</type> are specified using the following syntax:

Values of type <type>path</type> are specified using any of the following

syntaxes:

<synopsis>

( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )

[ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) ]

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>

( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>

</synopsis>

where the points are the end points of the line segments

comprising the path. Square brackets (<literal>[]</>) indicate

an open path, while parentheses (<literal>()</>) indicate a

closed path.

closed path. When the outermost parentheses are omitted, as

in the third through fifth syntaxes, a closed path is assumed.

</para>

<para>

<para>

Polygons are represented by lists of points (the vertexes of the

polygon). Polygons are very similar to closed paths, but are

stored differently

and have their own set of support routines.

stored differently and have their own set of support routines.

</para>

<para>

Values of type <type>polygon</type> are specified using the following syntax:

Values of type <type>polygon</type> are specified using any of the

following syntaxes:

<synopsis>

( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )

<replaceable>x1</replaceable> , <replaceable>y1</replaceable> , ... , <replaceable>xn</replaceable> , <replaceable>yn</replaceable>

</synopsis>

where the points are the end points of the line segments

<para>

Circles are represented by a center point and radius.

Values of type <type>circle</type> are specified using the following syntax:

Values of type <type>circle</type> are specified using any of the

following syntaxes:

<synopsis>

&lt; ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable> &gt;

( ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable> )

( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable>

<replaceable>x</replaceable> , <replaceable>y</replaceable> , <replaceable>r</replaceable>

( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable>

<replaceable>x</replaceable> , <replaceable>y</replaceable> , <replaceable>r</replaceable>

</synopsis>

where

<literal>(<replaceable>x</replaceable>,<replaceable>y</replaceable>)</literal>

is the center point and <replaceable>r</replaceable> is the radius of the circle.

<literal>(<replaceable>x</replaceable>,<replaceable>y</replaceable>)</>

is the center point and <replaceable>r</replaceable> is the radius of the

circle.

</para>

<para>