Index: includes/database/database.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/database/database.inc,v
retrieving revision 1.30
diff -u -r1.30 database.inc
--- includes/database/database.inc	29 Nov 2008 09:30:35 -0000	1.30
+++ includes/database/database.inc	1 Dec 2008 05:21:45 -0000
@@ -1243,11 +1243,20 @@
  * class DatabaseStatement_oracle extends PDOStatement implements DatabaseStatementInterface {}
  * @endcode
  *
- * or implement their own class, but in that case they will also have to implement
- * the Iterator or IteratorArray interfaces before DatabaseStatementInterface:
+ * or implement their own class. For the latter, they will have to either
+ * implement the Iterator interface directly, ensuring Iterator appears BEFORE
+ * the DatabaseStatementInterface:
  * @code
  * class DatabaseStatement_oracle implements Iterator, DatabaseStatementInterface {}
  * @endcode
+ *
+ * or extend the ArrayIterator class:
+ * @code
+ * class DatabaseStatement_oracle extends ArrayIterator implements DatabaseStatementInterface {}
+ * @endcode
+ *
+ * In this final case, ArrayIterator itself implements Iterator, so there is no
+ * need to implement it explicitly.
  */
 interface DatabaseStatementInterface extends Traversable {