From: Regina Obe <lr@pcorp.us>
Date: Tue, 25 Oct 2016 18:38:56 +0000 (+0000)
Subject: get rid of invalid link and obsolete statements about ST_Collect
X-Git-Tag: 2.4.0alpha~223
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c326eea22f710d27ecdc091c831e0e81b1421505;p=postgis

get rid of invalid link and obsolete statements about ST_Collect

git-svn-id: http://svn.osgeo.org/postgis/trunk@15214 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml
index 2b27710f0..84e3ffd21 100644
--- a/doc/reference_processing.xml
+++ b/doc/reference_processing.xml
@@ -472,13 +472,10 @@ SELECT ST_ClipByBox2D(the_geom, ST_MakeEnvelope(0,0,10,10)) FROM mytab;
 			input geometries. Output type can be a MULTI* or a
 			GEOMETRYCOLLECTION.</para>
 
-		<note><para>ST_Collect and ST_Union are often interchangeable.
-			ST_Collect is in general orders of magnitude faster than ST_Union
-			because it does not try to dissolve boundaries or validate that a constructed MultiPolgon doesn't
-			have overlapping regions. It merely rolls up
-			single geometries into MULTI and MULTI or mixed geometry types
-			into Geometry Collections. Unfortunately geometry collections are
-			not well-supported by GIS tools. To prevent ST_Collect from
+		<note><para>ST_Collect and ST_Union are often interchangeable except that ST_Collect will always return a GeometryCollection or MULTI geometry
+		and ST_Union may return single geometries when it dissolves boundaries.  ST_Union will also split linestrings at node intersections, whereas ST_Collect
+		will never split linestrings and in turn just return as MULTILINESTRING.
+			 To prevent ST_Collect from
 			returning a Geometry Collection when collecting MULTI geometries,
 			one can use the below trick that utilizes <xref linkend="ST_Dump" /> to expand the
 			MULTIs out to singles and then regroup them.</para></note>
@@ -492,9 +489,8 @@ SELECT ST_ClipByBox2D(the_geom, ST_MakeEnvelope(0,0,10,10)) FROM mytab;
 
 	  <refsection>
 		<title>Examples</title>
-		<para>Aggregate example (<ulink url="http://postgis.refractions.net/pipermail/postgis-users/2008-June/020331.html">http://postgis.refractions.net/pipermail/postgis-users/2008-June/020331.html</ulink>)</para>
-			<programlisting>SELECT stusps,
-	   ST_Multi(ST_Collect(f.the_geom)) as singlegeom
+		<para>Aggregate example</para>
+			<programlisting>SELECT stusps, ST_Collect(f.the_geom) as singlegeom
 	 FROM (SELECT stusps, (ST_Dump(the_geom)).geom As the_geom
 				FROM
 				somestatetable ) As f