diff --git a/lib/database/schema.inc.php b/lib/database/schema.inc.php
index 67e6363..dcca76a 100644
--- a/lib/database/schema.inc.php
+++ b/lib/database/schema.inc.php
@@ -9,31 +9,31 @@
  * Document Management Made Simple
  * Copyright (C) 2008 KnowledgeTree Inc.
  * Portions copyright The Jam Warehouse Software (Pty) Limited
- * 
+ *
  * This program is free software; you can redistribute it and/or modify it under
  * the terms of the GNU General Public License version 3 as published by the
  * Free Software Foundation.
- * 
+ *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  * details.
- * 
+ *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- * 
- * You can contact KnowledgeTree Inc., PO Box 7775 #87847, San Francisco, 
+ *
+ * You can contact KnowledgeTree Inc., PO Box 7775 #87847, San Francisco,
  * California 94120-7775, or email info@knowledgetree.com.
- * 
+ *
  * The interactive user interfaces in modified source and object code versions
  * of this program must display Appropriate Legal Notices, as required under
  * Section 5 of the GNU General Public License version 3.
- * 
+ *
  * In accordance with Section 7(b) of the GNU General Public License version 3,
  * these Appropriate Legal Notices must retain the display of the "Powered by
- * KnowledgeTree" logo and retain the original copyright notice. If the display of the 
+ * KnowledgeTree" logo and retain the original copyright notice. If the display of the
  * logo is not reasonably feasible for technical reasons, the Appropriate Legal Notices
- * must display the words "Powered by KnowledgeTree" and retain the original 
+ * must display the words "Powered by KnowledgeTree" and retain the original
  * copyright notice.
  * Contributor( s): ______________________________________
  */
@@ -568,6 +568,7 @@ class KTSchemaUtil
 		$this->defineIndex('document_transaction_types_lookup','namespace', 'UNIQUE');
 
 		$this->defineIndex('document_transactions','session_id');
+		$this->defineIndex('document_transactions','user_id');
 		$this->defineIndex('document_transactions','document_id');
 
 		$this->defineIndex('document_types_lookup','name');
diff --git a/sql/mysql/install/data.sql b/sql/mysql/install/data.sql
index 8478d12..c9511eb 100644
--- a/sql/mysql/install/data.sql
+++ b/sql/mysql/install/data.sql
@@ -1724,7 +1724,8 @@ INSERT INTO `upgrades` VALUES
 (203,'sql*3.5.3*0*3.5.3/saved_search.sql','Fix saved search table to support long expressions.','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3'),
 (204,'sql*3.5.3*0*3.5.3/preview_column.sql','Adjust Preview Column.','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3'),
 (205,'sql*3.5.3*0*3.5.3/tag_cloud.sql','Update TagCloud descritption.','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3'),
-(206,'upgrade*3.5.3*99*upgrade3.5.3','Upgrade from version 3.5.2 to 3.5.3','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3');
+(206,'sql*3.5.3*0*3.5.3/doc_tran_user_index.sql','Add index on user_id to document transactions table.','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3'),
+(207,'upgrade*3.5.3*99*upgrade3.5.3','Upgrade from version 3.5.2 to 3.5.3','2008-07-30 00:00:00',1,'upgrade*3.5.3*99*upgrade3.5.3');
 /*!40000 ALTER TABLE `upgrades` ENABLE KEYS */;
 UNLOCK TABLES;
 
@@ -2655,7 +2656,7 @@ UNLOCK TABLES;
 LOCK TABLES `zseq_upgrades` WRITE;
 /*!40000 ALTER TABLE `zseq_upgrades` DISABLE KEYS */;
 INSERT INTO `zseq_upgrades` VALUES
-(206);
+(207);
 /*!40000 ALTER TABLE `zseq_upgrades` ENABLE KEYS */;
 UNLOCK TABLES;
 
diff --git a/sql/mysql/install/structure.sql b/sql/mysql/install/structure.sql
index 74dadf7..5ec79f7 100644
--- a/sql/mysql/install/structure.sql
+++ b/sql/mysql/install/structure.sql
@@ -523,6 +523,7 @@ CREATE TABLE `document_transactions` (
   PRIMARY KEY  (`id`),
   KEY `session_id` (`session_id`),
   KEY `document_id` (`document_id`),
+  KEY `user_id` (`user_id`),
   KEY `datetime` (`datetime`,`transaction_namespace`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
diff --git a/sql/mysql/upgrade/3.5.3/doc_tran_user_index.sql b/sql/mysql/upgrade/3.5.3/doc_tran_user_index.sql
new file mode 100644
index 0000000..41b9d51
--- /dev/null
+++ b/sql/mysql/upgrade/3.5.3/doc_tran_user_index.sql
@@ -0,0 +1 @@
+alter table `ktdms`.`document_transactions` add index `user_id` (`user_id`);
\ No newline at end of file