Re: PoC/WIP: Extended statistics on expressions

I suggest to add some kind of reference to stats expressions here.

--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml

  <sect2 id="vacuum-for-statistics">
   <title>Updating Planner Statistics</title>

   <indexterm zone="vacuum-for-statistics">
    <primary>statistics</primary>
    <secondary>of the planner</secondary>
   </indexterm>

[...]

@@ -330,10 +330,12 @@
 
     <para>
      Also, by default there is limited information available about
-     the selectivity of functions.  However, if you create an expression
+     the selectivity of functions.  However, if you create a statistics
+     expression or an expression
      index that uses a function call, useful statistics will be
      gathered about the function, which can greatly improve query
      plans that use the expression index.


-- 
Justin