doc: Add index entry for "hypothetical-set aggregate"

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 8fa8d8f435d3e9efc2c0a1e29ae49c1f0577bbef..386fd425b0ce4c835a0cae0d0e2271f6951af799 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -12904,6 +12904,11 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
    simply produces a null result.
   </para>
 
+  <indexterm>
+   <primary>hypothetical-set aggregate</primary>
+   <secondary>built-in</secondary>
+  </indexterm>
+
   <para>
    Each of the aggregates listed in
    <xref linkend="functions-hypothetical-table"> is associated with a