diff --git a/lib/database/schema.inc.php b/lib/database/schema.inc.php
index a781ed8..2a6986a 100644
--- a/lib/database/schema.inc.php
+++ b/lib/database/schema.inc.php
@@ -534,6 +534,8 @@ class KTSchemaUtil
 		$this->defineIndex('document_content_version','filename','','(255)');
 		$this->defineIndex('document_content_version','size');
 
+		$this->defineIndex('document_transactions',array('datetime','transaction_namespace'));
+
 		$this->defineIndex('field_behaviour_options',array('behaviour_id','field_id'));
 
 		$this->defineIndex('field_behaviours','name');
@@ -548,6 +550,7 @@ class KTSchemaUtil
 
 		$this->defineIndex('folder_transactions','folder_id');
 		$this->defineIndex('folder_transactions','session_id');
+
 		$this->defineIndex('folders', array('parent_id','name'));
 
 		$this->defineIndex('groups_lookup','name', 'UNIQUE');
diff --git a/sql/mysql/install/structure.sql b/sql/mysql/install/structure.sql
index 79d9595..5673bdd 100644
--- a/sql/mysql/install/structure.sql
+++ b/sql/mysql/install/structure.sql
@@ -485,7 +485,8 @@ CREATE TABLE `document_transactions` (
   `admin_mode` tinyint(1) NOT NULL default '0',
   PRIMARY KEY  (`id`),
   KEY `session_id` (`session_id`),
-  KEY `document_id` (`document_id`)
+  KEY `document_id` (`document_id`),
+  KEY (`datetime`,`transaction_namespace`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
 --
diff --git a/sql/mysql/upgrade/3.5.2/document_transactions.sql b/sql/mysql/upgrade/3.5.2/document_transactions.sql
index 6327c9a..38134de 100644
--- a/sql/mysql/upgrade/3.5.2/document_transactions.sql
+++ b/sql/mysql/upgrade/3.5.2/document_transactions.sql
@@ -2,4 +2,5 @@ alter table document_transactions change version version varchar(50);
 alter table document_transactions change ip ip varchar(15);
 alter table document_transactions change filename filename mediumtext;
 alter table document_transactions change comment comment mediumtext;
-alter table document_transactions change transaction_namespace transaction_namespace varchar(255);
\ No newline at end of file
+alter table document_transactions change transaction_namespace transaction_namespace varchar(255);
+alter table document_transactions add index (`datetime`,`transaction_namespace`);
\ No newline at end of file