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postgresql-docs-7.4.1-2.5.100mdk.i586.rpm

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>Geometric Types</TITLE
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>PostgreSQL 7.4.1 Documentation</TH
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CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="DATATYPE-GEOMETRIC"
>8.7. Geometric Types</A
></H1
><P
>    Geometric data types represent two-dimensional spatial
    objects. <A
HREF="datatype-geometric.html#DATATYPE-GEO-TABLE"
>Table 8-16</A
> shows the geometric
    types available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>.  The
    most fundamental type, the point, forms the basis for all of the
    other types.
   </P
><DIV
CLASS="TABLE"
><A
NAME="DATATYPE-GEO-TABLE"
></A
><P
><B
>Table 8-16. Geometric Types</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Storage Size</TH
><TH
>Representation</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="TYPE"
>point</TT
></TD
><TD
>16 bytes</TD
><TD
>Point on the plane</TD
><TD
>(x,y)</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>line</TT
></TD
><TD
>32 bytes</TD
><TD
>Infinite line (not fully implemented)</TD
><TD
>((x1,y1),(x2,y2))</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>lseg</TT
></TD
><TD
>32 bytes</TD
><TD
>Finite line segment</TD
><TD
>((x1,y1),(x2,y2))</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>box</TT
></TD
><TD
>32 bytes</TD
><TD
>Rectangular box</TD
><TD
>((x1,y1),(x2,y2))</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>path</TT
></TD
><TD
>16+16n bytes</TD
><TD
>Closed path (similar to polygon)</TD
><TD
>((x1,y1),...)</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>path</TT
></TD
><TD
>16+16n bytes</TD
><TD
>Open path</TD
><TD
>[(x1,y1),...]</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>polygon</TT
></TD
><TD
>40+16n bytes</TD
><TD
>Polygon (similar to closed path)</TD
><TD
>((x1,y1),...)</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>circle</TT
></TD
><TD
>24 bytes</TD
><TD
>Circle</TD
><TD
>&#60;(x,y),r&#62; (center and radius)</TD
></TR
></TBODY
></TABLE
></DIV
><P
>    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 <A
HREF="functions-geometry.html"
>Section 9.9</A
>.
   </P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4739"
>8.7.1. Points</A
></H2
><A
NAME="AEN4741"
></A
><P
>     Points are the fundamental two-dimensional building block for geometric types.
     Values of type <TT
CLASS="TYPE"
>point</TT
> are specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>( <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
> )
  <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
></PRE
><P>

     where <VAR
CLASS="REPLACEABLE"
>x</VAR
> and <VAR
CLASS="REPLACEABLE"
>y</VAR
> are the respective
     coordinates as floating-point numbers.
    </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4752"
>8.7.2. Line Segments</A
></H2
><A
NAME="AEN4754"
></A
><A
NAME="AEN4756"
></A
><P
>     Line segments (<TT
CLASS="TYPE"
>lseg</TT
>) are represented by pairs of points.
     Values of type <TT
CLASS="TYPE"
>lseg</TT
> are specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>( ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ( <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
> ) )
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ( <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
> )  
    <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   ,   <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
></PRE
><P>

     where
     <TT
CLASS="LITERAL"
>(<VAR
CLASS="REPLACEABLE"
>x1</VAR
>,<VAR
CLASS="REPLACEABLE"
>y1</VAR
>)</TT
>
     and
     <TT
CLASS="LITERAL"
>(<VAR
CLASS="REPLACEABLE"
>x2</VAR
>,<VAR
CLASS="REPLACEABLE"
>y2</VAR
>)</TT
>
     are the end points of the line segment.
    </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4780"
>8.7.3. Boxes</A
></H2
><A
NAME="AEN4782"
></A
><A
NAME="AEN4784"
></A
><P
>     Boxes are represented by pairs of points that are opposite
     corners of the box.
     Values of type <TT
CLASS="TYPE"
>box</TT
> is specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>( ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ( <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
> ) )
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ( <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
> )  
    <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   ,   <VAR
CLASS="REPLACEABLE"
>x2</VAR
> , <VAR
CLASS="REPLACEABLE"
>y2</VAR
></PRE
><P>

     where
     <TT
CLASS="LITERAL"
>(<VAR
CLASS="REPLACEABLE"
>x1</VAR
>,<VAR
CLASS="REPLACEABLE"
>y1</VAR
>)</TT
>
     and
     <TT
CLASS="LITERAL"
>(<VAR
CLASS="REPLACEABLE"
>x2</VAR
>,<VAR
CLASS="REPLACEABLE"
>y2</VAR
>)</TT
>
     are the opposite corners of the box.
    </P
><P
>     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 corners.
    </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4808"
>8.7.4. Paths</A
></H2
><A
NAME="AEN4810"
></A
><P
>     Paths are represented by connected sets of points. Paths can be
     <I
CLASS="FIRSTTERM"
>open</I
>, where
     the first and last points in the set are not connected, and <I
CLASS="FIRSTTERM"
>closed</I
>,
     where the first and last point are connected. The functions
     <CODE
CLASS="FUNCTION"
>popen(<VAR
CLASS="REPLACEABLE"
>p</VAR
>)</CODE
>
     and
     <CODE
CLASS="FUNCTION"
>pclose(<VAR
CLASS="REPLACEABLE"
>p</VAR
>)</CODE
>
     are supplied to force a path to be open or closed, and the functions
     <CODE
CLASS="FUNCTION"
>isopen(<VAR
CLASS="REPLACEABLE"
>p</VAR
>)</CODE
>
     and
     <CODE
CLASS="FUNCTION"
>isclosed(<VAR
CLASS="REPLACEABLE"
>p</VAR
>)</CODE
>
     are supplied to test for either type in an expression.
    </P
><P
>     Values of type <TT
CLASS="TYPE"
>path</TT
> are specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>( ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ... , ( <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> ) )
[ ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ... , ( <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> ) ]
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ... , ( <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> )  
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   , ... ,   <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> )  
    <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   , ... ,   <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
>    </PRE
><P>

     where the points are the end points of the line segments
     comprising the path.  Square brackets (<TT
CLASS="LITERAL"
>[]</TT
>) indicate
     an open path, while parentheses (<TT
CLASS="LITERAL"
>()</TT
>) indicate a
     closed path.
    </P
><P
>     Paths are output using the first syntax.
    </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4849"
>8.7.5. Polygons</A
></H2
><A
NAME="AEN4851"
></A
><P
>     Polygons are represented by sets of points. Polygons should probably be
     considered equivalent to closed paths, but are stored differently 
     and have their own set of support routines.
    </P
><P
>     Values of type <TT
CLASS="TYPE"
>polygon</TT
> are specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>( ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ... , ( <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> ) )
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
> ) , ... , ( <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> )  
  ( <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   , ... ,   <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
> )  
    <VAR
CLASS="REPLACEABLE"
>x1</VAR
> , <VAR
CLASS="REPLACEABLE"
>y1</VAR
>   , ... ,   <VAR
CLASS="REPLACEABLE"
>xn</VAR
> , <VAR
CLASS="REPLACEABLE"
>yn</VAR
>    </PRE
><P>

     where the points are the end points of the line segments
     comprising the boundary of the polygon.
    </P
><P
>     Polygons are output using the first syntax.
    </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN4874"
>8.7.6. Circles</A
></H2
><A
NAME="AEN4876"
></A
><P
>     Circles are represented by a center point and a radius.
     Values of type <TT
CLASS="TYPE"
>circle</TT
> are specified using the following syntax:

</P><PRE
CLASS="SYNOPSIS"
>&lt; ( <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
> ) , <VAR
CLASS="REPLACEABLE"
>r</VAR
> &gt;
( ( <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
> ) , <VAR
CLASS="REPLACEABLE"
>r</VAR
> )
  ( <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
> ) , <VAR
CLASS="REPLACEABLE"
>r</VAR
>  
    <VAR
CLASS="REPLACEABLE"
>x</VAR
> , <VAR
CLASS="REPLACEABLE"
>y</VAR
>   , <VAR
CLASS="REPLACEABLE"
>r</VAR
>  </PRE
><P>

     where
     <TT
CLASS="LITERAL"
>(<VAR
CLASS="REPLACEABLE"
>x</VAR
>,<VAR
CLASS="REPLACEABLE"
>y</VAR
>)</TT
>
     is the center and <VAR
CLASS="REPLACEABLE"
>r</VAR
> is the radius of the circle.
    </P
><P
>     Circles are output using the first syntax.
    </P
></DIV
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