[postgis-tickets] r15712 - #3844 Update docs to match new = operator behaviour

[Paul Ramsey]

Author: pramsey
Date: 2017-09-13 13:03:07 -0700 (Wed, 13 Sep 2017)
New Revision: 15712

Modified:
   trunk/doc/reference_operator.xml
Log:
#3844 Update docs to match new = operator behaviour


Modified: trunk/doc/reference_operator.xml
===================================================================
--- trunk/doc/reference_operator.xml	2017-09-13 17:22:03 UTC (rev 15711)
+++ trunk/doc/reference_operator.xml	2017-09-13 20:03:07 UTC (rev 15712)
@@ -963,27 +963,25 @@
 		  <refsection>
 			<title>Description</title>
 
-			<para>The <varname>=</varname> operator returns <varname>TRUE</varname> if the bounding box of geometry/geography A
-			is the same as the bounding box of geometry/geography B.  PostgreSQL uses the =, <, and > operators defined for geometries to
+			<para>The <varname>=</varname> operator returns <varname>TRUE</varname> if the coordinates and coordinate order geometry/geography A
+			are the same as the coordinates and coordinate order of geometry/geography B.  PostgreSQL uses the =, <, and > operators defined for geometries to
 			perform internal orderings and comparison of geometries (ie. in a GROUP BY or ORDER BY clause).</para>
 
-			<warning>
-			  <para>This is cause for a lot of confusion. When you compare geometryA =
-			  geometryB it will return true even when the geometries are clearly
-			  different IF their bounding boxes are the same. To check for true
-			  equality use <xref linkend="ST_OrderingEquals" /> or <xref
-			  linkend="ST_Equals" /></para>
-			</warning>
+			<note>
+			  <para>Only geometry/geography that are exactly equal in all respects,
+          with the same coordinates, in the same order, are considered
+          equal by this operator. For "spatial equality", that ignores
+          things like coordinate order, and can detect features that 
+          cover the same spatial area with different representations,  
+          use <xref linkend="ST_OrderingEquals" /> 
+          or <xref linkend="ST_Equals" /></para>
+			</note>
 
 			<caution><para>This operand will NOT make use of any indexes that may be available on the
-				geometries.</para></caution>
+				geometries. For an index assisted exact equality test, combine = with &&.</para></caution>
 
 			<para>&curve_support;</para>
 			<para>&P_support;</para>
-			<para>Changed:  2.0.0 , the bounding box of geometries was changed to use double precision instead of float4 precision of
-			prior. The side effect of this is that in particular points in prior versions that were a little different may have returned
-				true in prior versions and false in 2.0+ since their float4 boxes would be the same but there float8 (double precision), would be
-				different.</para>
 
 		  </refsection>