Commit 1f34cab0 authored by Sandro Santilli's avatar Sandro Santilli

Further reword docs for <-> and <#> operators

.. makeing clear KNN is only available with PgSQL 9.1+

git-svn-id: http://svn.osgeo.org/postgis/[email protected] b70326c6-7e19-0410-871a-916f4a2858ee
parent 93c68c82
......@@ -1109,7 +1109,7 @@ ordering.</para>
<note><para>Index only kicks in if one of the geometries is a constant (not in a subquery/cte). e.g. 'SRID=3005;POINT(1011102 450541)'::geometry instead of a.geom</para></note>
<para>Refer to <ulink url="http://workshops.opengeo.org/postgis-intro/knn.html">OpenGeo workshop: Nearest-Neighbour Searching</ulink> for real live example.</para>
<para>Availability: 2.0.0 only available for PostgreSQL 9.1+</para>
<para>Availability: 2.0.0 -- KNN only available for PostgreSQL 9.1+</para>
</refsection>
......@@ -1196,8 +1196,9 @@ Finally the hybrid:
<refnamediv>
<refname>&lt;#&gt;</refname>
<refpurpose>Returns the distance between bounding box of 2 geometries. For point / point checks it's almost the same as distance (though may be different since the bounding box is at floating point accuracy and geometries are double precision). Useful for doing distance ordering and nearest neighbor limits
using KNN gist functionality.</refpurpose>
<refpurpose>
Returns the 2D distance between bounding boxes of 2 geometries.
</refpurpose>
</refnamediv>
<refsynopsisdiv>
......@@ -1223,14 +1224,14 @@ Finally the hybrid:
<refsection>
<title>Description</title>
<para>The <varname>&lt;#&gt;</varname> KNN GIST operator returns distance between two floating point bounding boxes read from the spatial index if available. Useful for doing nearest neighbor <emphasis role="strong">approximate</emphasis> distance ordering.</para>
<para>The <varname>&lt;#&gt;</varname> operator returns distance between two floating point bounding boxes, possibly reading them from a spatial index (PostgreSQL 9.1+ required). Useful for doing nearest neighbor <emphasis role="strong">approximate</emphasis> distance ordering.</para>
<note><para>This operand will make use of any indexes that may be available on the
geometries. It is different from other operators that use spatial indexes in that the spatial index is only used when the operator
is in the ORDER BY clause.</para></note>
<note><para>Index only kicks in if one of the geometries is a constant e.g. ORDER BY (ST_GeomFromText('POINT(1 2)') &lt;#&gt; geom) instead of g1.geom &lt;#&gt;.</para></note>
<para>Availability: 2.0.0 only available for PostgreSQL 9.1+</para>
<para>Availability: 2.0.0 -- KNN only available for PostgreSQL 9.1+</para>
</refsection>
......
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