diff --git a/src/applications/fact/extract/PhabricatorFactUpdateIterator.php b/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
index b7c59a4499..be93cf62c1 100644
--- a/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
+++ b/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
@@ -1,86 +1,91 @@
 <?php
 
 /*
  * Copyright 2012 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 /**
  * Iterate over objects by update time in a stable way. This iterator only works
  * for "normal" Lisk objects: objects with an autoincrement ID and a
  * dateModified column.
  */
 final class PhabricatorFactUpdateIterator extends PhutilBufferedIterator {
 
   private $cursor;
   private $object;
   private $position;
   private $ignoreUpdatesDuration = 15;
 
+  private $set;
+
   public function __construct(LiskDAO $object) {
-    $this->object = $object;
+    $this->set = new LiskDAOSet();
+    $this->object = $object->putInSet($this->set);
     $this->position = '0:0';
   }
 
   public function setPosition($position) {
     $this->position = $position;
     return $this;
   }
 
   protected function didRewind() {
     $this->cursor = $this->position;
   }
 
   protected function getCursorFromObject($object) {
     return $object->getDateModified().':'.$object->getID();
   }
 
   public function key() {
     return $this->getCursorFromObject($this->current());
   }
 
   protected function loadPage() {
     list($after_epoch, $after_id) = explode(':', $this->cursor);
 
+    $this->set->clearSet();
+
     // NOTE: We ignore recent updates because once we process an update we'll
     // never process rows behind it again. We need to read only rows which
     // we're sure no new rows will be inserted behind. If we read a row that
     // was updated on the current second, another update later on in this second
     // could affect an object with a lower ID, and we'd skip that update. To
     // avoid this, just ignore any rows which have been updated in the last few
     // seconds. This also reduces the amount of work we need to do if an object
     // is repeatedly updated; we will just look at the end state without
     // processing the intermediate states. Finally, this gives us reasonable
     // protections against clock skew between the machine the daemon is running
     // on and any machines performing writes.
 
     $page = $this->object->loadAllWhere(
       '((dateModified > %d) OR (dateModified = %d AND id > %d))
         AND (dateModified < %d - %d)
         ORDER BY dateModified ASC, id ASC LIMIT %d',
       $after_epoch,
       $after_epoch,
       $after_id,
       time(),
       $this->ignoreUpdatesDuration,
       $this->getPageSize());
 
     if ($page) {
       $this->cursor = $this->getCursorFromObject(end($page));
     }
 
     return $page;
   }
 
 }
diff --git a/src/infrastructure/storage/lisk/LiskDAOSet.php b/src/infrastructure/storage/lisk/LiskDAOSet.php
index 1b343b96a4..6d8ebc4483 100644
--- a/src/infrastructure/storage/lisk/LiskDAOSet.php
+++ b/src/infrastructure/storage/lisk/LiskDAOSet.php
@@ -1,85 +1,101 @@
 <?php
 
 /*
  * Copyright 2012 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 /**
  * You usually don't need to use this class directly as it is controlled by
  * @{class:LiskDAO}. You can create it if you want to work with objects of same
  * type from different sources as with one set. Let's say you want to get
  * e-mails of all users involved in a revision:
  *
  *   $users = new LiskDAOSet();
  *   $users->addToSet($author);
  *   foreach ($reviewers as $reviewer) {
  *     $users->addToSet($reviewer);
  *   }
  *   foreach ($ccs as $cc) {
  *     $users->addToSet($cc);
  *   }
  *   // Preload e-mails of all involved users and return e-mails of author.
  *   $author_emails = $author->loadRelatives(
  *     new PhabricatorUserEmail(),
  *     'userPHID',
  *     'getPHID');
  */
 final class LiskDAOSet {
   private $daos = array();
   private $relatives = array();
+  private $subsets = array();
 
   public function addToSet(LiskDAO $dao) {
     $this->daos[] = $dao;
     $dao->putInSet($this);
     return $this;
   }
 
+  /**
+   * The main purpose of this method is to break cyclic dependency.
+   * It removes all objects from this set and all subsets created by it.
+   */
+  final public function clearSet() {
+    $this->daos = array();
+    $this->relatives = array();
+    foreach ($this->subsets as $set) {
+      $set->clearSet();
+    }
+    return $this;
+  }
+
+
   /**
    * See @{method:LiskDAO::loadRelatives}.
    */
   public function loadRelatives(
     LiskDAO $object,
     $foreign_column,
     $key_method = 'getID',
     $where = '') {
 
     $relatives = &$this->relatives[
       get_class($object)."-{$foreign_column}-{$key_method}-{$where}"];
 
     if ($relatives === null) {
       $ids = array();
       foreach ($this->daos as $dao) {
         $id = $dao->$key_method();
         if ($id !== null) {
           $ids[$id] = $id;
         }
       }
       if (!$ids) {
         $relatives = array();
       } else {
         $set = new LiskDAOSet();
+        $this->subsets[] = $set;
         $relatives = $object->putInSet($set)->loadAllWhere(
           '%C IN (%Ls) %Q',
           $foreign_column,
           $ids,
           ($where != '' ? 'AND '.$where : ''));
         $relatives = mgroup($relatives, 'get'.$foreign_column);
       }
     }
 
     return $relatives;
   }
 
 }