Index: includes/query.inc
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/views/includes/query.inc,v
retrieving revision 1.15
diff -u -F^f -r1.15 query.inc
--- includes/query.inc	22 Apr 2008 05:34:03 -0000	1.15
+++ includes/query.inc	8 May 2008 21:59:53 -0000
@@ -375,6 +375,37 @@
     }
 
     if ($this->ensure_path($table, $relationship, $join)) {
+
+      // Attempt to eliminate redundant joins.  If this table's
+      // relationship and join exactly matches an existing table's
+      // relationship and join, we do not have to join to it again;
+      // just return the existing table's alias.  See
+      // http://groups.drupal.org/node/11288 for details.
+      //
+      // TODO: Scanning through $this->table_queue results in an
+      // O(N^2) algorithm.  N is small but we can probably do better.
+
+      // If we do not have join info, get it the same way queue_table
+      // will get it.
+      //
+      // TODO: I do not yet grok adjust_join().
+      if (! isset($join)) {
+        $join = $this->get_join_data($table, $this->relationships[$relationship]['base']);
+      }
+
+      // If we have join info, scan through the table queue to see if
+      // a matching join and relationship exists.  If so, use it.
+      if (isset($join)) {
+        foreach ($this->table_queue as $quetab) {
+          // In PHP 4 and 5, the == operation returns TRUE for two objects
+          // if they are instances of the same class and have the same
+          // attributes and values.
+          if ($quetab['relationship'] == $relationship && $quetab['join'] == $join) {
+            return $quetab['table'];
+          }
+        }
+      }
+        
       return $this->queue_table($table, $relationship, $join);
     }
   }