Document ST_UnaryUnion

git-svn-id: http://svn.osgeo.org/postgis/trunk@6830 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml
index 228d6bfb2b863789f86b28921d385f623b331bcf..568209939e3074222e51e3d5a563e9023e253a4d 100644 (file)
--- a/doc/reference_processing.xml
+++ b/doc/reference_processing.xml
@@ -2496,9 +2496,69 @@ MULTILINESTRING((3 4,4 5),(1 2,3 4))
          </refsection>
          <refsection>
                <title>See Also</title>
-               <para><xref linkend="ST_Collect" /></para>
+               <para>
+                       <xref linkend="ST_Collect" />
+                       <xref linkend="ST_UnaryUnion" />
+               </para>
+         </refsection>
+       </refentry>
+
+       <refentry id="ST_UnaryUnion">
+         <refnamediv>
+               <refname>ST_UnaryUnion</refname>
+
+               <refpurpose>Like ST_Union, but working at the geometry component level.</refpurpose>
+         </refnamediv>
+
+         <refsynopsisdiv>
+               <funcsynopsis>
+                 <funcprototype>
+                       <funcdef>geometry <function>ST_UnaryUnion</function></funcdef>
+                       <paramdef><type>geometry </type> <parameter>geom</parameter></paramdef>
+                 </funcprototype>
+
+               </funcsynopsis>
+         </refsynopsisdiv>
+
+         <refsection>
+               <title>Description</title>
+
+               <para>
+               Unlike ST_Union, ST_UnaryUnion does dissolve boundaries
+               between components of a multipolygon (invalid)
+               and does perform union between the components of a
+               geometrycollection.
+               Each components of the input geometry is assumed to be
+               valid, so you won't get a valid multipolygon out of a
+               bow-tie polygon (invalid).
+               </para>
+
+               <para>
+               You may use this function to node a set of linestrings.
+               You may mix ST_UnaryUnion with ST_Collect to fine-tune
+               how many geometries at once you want to dissolve to
+               be nice on both memory size and CPU time, finding the
+               balance between ST_Union and ST_MemUnion.
+               </para>
+
+               <para>&Z_support;</para>
+
+               <para>Availability: 2.0.0 - requires GEOS &gt;= 3.3.0.</para>
+         </refsection>
+
+
+         <!-- Optionally add a "See Also" section -->
+         <refsection>
+               <title>See Also</title>
+
+               <para>
+                       <xref linkend="ST_Union" />
+                       <xref linkend="ST_MemUnion" />
+                       <xref linkend="ST_Collect" />
+               </para>
          </refsection>
        </refentry>
 
 
+
 </sect1>