diff --git a/workflow/engine/config/schema.xml b/workflow/engine/config/schema.xml
index bf73a609d..6ec34406c 100644
--- a/workflow/engine/config/schema.xml
+++ b/workflow/engine/config/schema.xml
@@ -612,6 +612,9 @@
       <rule name="maxLength" value="32" message="User UID can be no larger than ${value} in size"/>
       <rule name="required" message="User UID is required."/>
     </validator>
+    <index name="indexForUsrUid">
+      <index-column name="USR_UID"/>
+    </index>
   </table>
   <table name="HOLIDAY" idMethod="native">
     <vendor type="mysql">
diff --git a/workflow/engine/data/mysql/schema.sql b/workflow/engine/data/mysql/schema.sql
index adff561d6..c7c3fd653 100644
--- a/workflow/engine/data/mysql/schema.sql
+++ b/workflow/engine/data/mysql/schema.sql
@@ -282,7 +282,8 @@ CREATE TABLE `GROUP_USER`
 (
 	`GRP_UID` VARCHAR(32) default '0' NOT NULL,
 	`USR_UID` VARCHAR(32) default '0' NOT NULL,
-	PRIMARY KEY (`GRP_UID`,`USR_UID`)
+	PRIMARY KEY (`GRP_UID`,`USR_UID`),
+	KEY `indexForUsrUid`(`USR_UID`)
 )ENGINE=InnoDB  DEFAULT CHARSET='utf8';
 #-----------------------------------------------------------------------------
 #-- HOLIDAY