diff --git a/lib/db/install.xml b/lib/db/install.xml
index b9b900372d2..8e4dd6215f0 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="lib/db" VERSION="20180403" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20180618" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -2638,7 +2638,11 @@
       </FIELDS>
       <KEYS>
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
+        <KEY NAME="fk_user" TYPE="foreign" FIELDS="userid" REFTABLE="user" REFFIELDS="id"/>
       </KEYS>
+      <INDEXES>
+        <INDEX NAME="ix_concomitem" UNIQUE="false" FIELDS="contextid, commentarea, itemid" COMMENT="Allows the comments API to load comments for a particular area effectively."/>
+      </INDEXES>
     </TABLE>
     <TABLE NAME="external_services" COMMENT="built in and custom external services">
       <FIELDS>
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index cc7edbd15a3..7ddc87689a3 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -2233,5 +2233,26 @@ function xmldb_main_upgrade($oldversion) {
     // Automatically generated Moodle v3.5.0 release upgrade line.
     // Put any upgrade step following this.
 
+    if ($oldversion < 2018062800.01) {
+        // Add foreign key fk_user to the comments table.
+        $table = new xmldb_table('comments');
+        $key = new xmldb_key('fk_user', XMLDB_KEY_FOREIGN, array('userid'), 'user', array('id'));
+        $dbman->add_key($table, $key);
+
+        upgrade_main_savepoint(true, 2018062800.01);
+    }
+
+    if ($oldversion < 2018062800.02) {
+        // Add composite index ix_concomitem to the table comments.
+        $table = new xmldb_table('comments');
+        $index = new xmldb_index('ix_concomitem', XMLDB_INDEX_NOTUNIQUE, array('contextid', 'commentarea', 'itemid'));
+
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        upgrade_main_savepoint(true, 2018062800.02);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index d6966f378ef..be6a9625b9e 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2018062800.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2018062800.02;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.