diff --git a/lib/db/install.xml b/lib/db/install.xml
index c8cda523452..b29a3f84417 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -1925,6 +1925,7 @@
       <INDEXES>
         <INDEX NAME="action" UNIQUE="false" FIELDS="action" COMMENT="insert/update/delete"/>
         <INDEX NAME="timemodified" UNIQUE="false" FIELDS="timemodified"/>
+        <INDEX NAME="userid-itemid-timemodified" UNIQUE="false" FIELDS="userid, itemid, timemodified" COMMENT="Improve history searching"/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="grade_import_newitem" COMMENT="temporary table for storing new grade_item names from grade import">
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 1232d832af9..7e04aed3524 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -1399,5 +1399,22 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2016021500.00);
     }
 
+    if ($oldversion < 2016021501.00) {
+        // This could take a long time. Unfortunately, no way to know how long, and no way to do progress, so setting for 1 hour.
+        upgrade_set_timeout(3600);
+
+        // Define index userid-itemid (not unique) to be added to grade_grades_history.
+        $table = new xmldb_table('grade_grades_history');
+        $index = new xmldb_index('userid-itemid-timemodified', XMLDB_INDEX_NOTUNIQUE, array('userid', 'itemid', 'timemodified'));
+
+        // Conditionally launch add index userid-itemid.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2016021501.00);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 231fd2404cc..65284140c1a 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2016021500.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2016021501.00;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.