[postgis-tickets] [SCM] PostGIS branch master updated. 3.1.0rc1-9-g000728d

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- Log -----------------------------------------------------------------
commit 000728dfda4b2b57eda4f809b029d19e68d95001
Author: Martin Davis <mtnclimb at gmail.com>
Date:   Wed Dec 16 16:59:33 2020 -0800

    Improve doc for ST_MultiPolygon

diff --git a/doc/reference_constructor.xml b/doc/reference_constructor.xml
index d231952..079a5b8 100644
--- a/doc/reference_constructor.xml
+++ b/doc/reference_constructor.xml
@@ -578,54 +578,58 @@ SELECT ST_MakePolygon( ST_ExteriorRing( ST_Buffer(ring.line,10)),
 FROM (SELECT ST_ExteriorRing(
 	ST_Buffer(ST_MakePoint(10,10),10,10)) AS line ) AS ring;
 </programlisting>
-		<para>Create a set of province boundaries with holes
-		representing lakes.  The input is a table of
-		province Polygons/MultiPolygons and a table of water linestrings.
-		Using a LEFT JOIN ensures all provinces are included even if they have no lakes.
-		</para>
-
-		<note><para>The CASE construct is used because passing a null array into
-		ST_MakePolygon results in a NULL return value.</para></note>
+    <para>Create a set of province boundaries with holes
+    representing lakes.  The input is a table of
+    province Polygons/MultiPolygons and a table of water linestrings.
+    Lines forming lakes are determined by using <xref linkend="ST_IsClosed" />.
+    The province linework is extracted by using
+    <xref linkend="ST_Boundary" />.
+    As required by <code>ST_MakePolygon</code>,
+    the boundary is forced to be a single LineString by using <xref linkend="ST_LineMerge" />.
+    (However, note that if a province has more than one region or has islands
+    this will produce an invallid polygon.)
+    Using a LEFT JOIN ensures all provinces are included even if they have no lakes.
+    </para>
+
+    <note><para>The CASE construct is used because passing a null array into
+    ST_MakePolygon results in a NULL return value.</para></note>
 
 		<programlisting>
-	SELECT p.gid, p.province_name,
-		CASE WHEN array_agg(w.the_geom) IS NULL
-		THEN p.the_geom
-		ELSE  ST_MakePolygon( ST_LineMerge(ST_Boundary(p.the_geom)), array_agg(w.the_geom)) END
-	FROM
-		provinces p LEFT JOIN waterlines w
-			ON (ST_Within(w.the_geom, p.the_geom) AND ST_IsClosed(w.the_geom))
-	GROUP BY p.gid, p.province_name, p.the_geom;
+SELECT p.gid, p.province_name,
+	CASE WHEN array_agg(w.geom) IS NULL
+	THEN p.geom
+	ELSE  ST_MakePolygon( ST_LineMerge(ST_Boundary(p.geom)),
+                        array_agg(w.geom)) END
+FROM
+	provinces p LEFT JOIN waterlines w
+		ON (ST_Within(w.geom, p.geom) AND ST_IsClosed(w.geom))
+GROUP BY p.gid, p.province_name, p.geom;
 </programlisting>
 
 	<para>Another technique is to utilize a correlated subquery
 	and the ARRAY() constructor that converts a row set to an array.</para>
 <programlisting>
-	SELECT p.gid,  p.province_name,
-		CASE WHEN EXISTS( SELECT w.the_geom
-			FROM waterlines w
-			WHERE ST_Within(w.the_geom, p.the_geom)
-			AND ST_IsClosed(w.the_geom))
-		THEN ST_MakePolygon(
-			ST_LineMerge(ST_Boundary(p.the_geom)),
-			ARRAY( SELECT w.the_geom
-				FROM waterlines w
-				WHERE ST_Within(w.the_geom, p.the_geom)
-				AND ST_IsClosed(w.the_geom)))
-		ELSE p.the_geom
-		END AS the_geom
-	FROM provinces p;
+SELECT p.gid,  p.province_name,
+    CASE WHEN EXISTS( SELECT w.geom
+        FROM waterlines w
+        WHERE ST_Within(w.geom, p.geom)
+        AND ST_IsClosed(w.geom))
+    THEN ST_MakePolygon(
+        ST_LineMerge(ST_Boundary(p.geom)),
+        ARRAY( SELECT w.geom
+            FROM waterlines w
+            WHERE ST_Within(w.geom, p.geom)
+            AND ST_IsClosed(w.geom)))
+    ELSE p.geom
+    END AS geom
+FROM provinces p;
 </programlisting>
 		</refsection>
 		<refsection>
 			<title>See Also</title>
 			<para>
-				<xref linkend="ST_Boundary" />,
-				<xref linkend="ST_AddPoint" />,
-				<xref linkend="ST_IsClosed" />,
-				<xref linkend="ST_LineMerge" />,
-				<xref linkend="ST_StartPoint" />,
 				<xref linkend="ST_BuildArea" />
+				<xref linkend="ST_Polygon" />
 			</para>
 		</refsection>
 	</refentry>

-----------------------------------------------------------------------

Summary of changes:
 doc/reference_constructor.xml | 74 +++++++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 35 deletions(-)


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