There's a subtle difference in the way MongoDBPlugin interprets an undefined sort param vs the core SEARCH implementation.

On MongoDB, it results in a request to sort on a field that isn't indexed, and on large webs this can result in an empty grid.

diff --git a/lib/Foswiki/Plugins/JQGridPlugin/SearchConnector.pm b/lib/Foswiki/Plugins/JQGridPlugin/SearchConnector.pm
index c874f3b..ae11855 100644
--- a/lib/Foswiki/Plugins/JQGridPlugin/SearchConnector.pm
+++ b/lib/Foswiki/Plugins/JQGridPlugin/SearchConnector.pm
@@ -97,7 +97,7 @@ sub restHandleSearch {
     }
   }
 
-  my $sort = $request->param('sidx') || '';
+  my $sort = $request->param('sidx') || 'Topic';
   my $sord = $request->param('sord') || 'asc';
   my $reverse = ($sord eq 'desc'?'on':'off');
 

-- PaulHarvey - 21 Nov 2011