diff --git a/lib/Doctrine/Hydrate.php b/lib/Doctrine/Hydrate.php
index 6c5037af5..02024ed09 100644
--- a/lib/Doctrine/Hydrate.php
+++ b/lib/Doctrine/Hydrate.php
@@ -179,8 +179,11 @@ class Doctrine_Hydrate extends Doctrine_Object implements Serializable
      */
     public function getRootAlias()
     {
-        $this->getSql();
-
+        if( !$this->_aliasMap )
+        {
+          $this->getSql();
+        }
+        
         reset($this->_aliasMap);
 
         return key($this->_aliasMap);