diff --git a/lib/dml/oci_native_moodle_database.php b/lib/dml/oci_native_moodle_database.php
index d4adcad881c..c57df245f83 100644
--- a/lib/dml/oci_native_moodle_database.php
+++ b/lib/dml/oci_native_moodle_database.php
@@ -1201,6 +1201,9 @@ class oci_native_moodle_database extends moodle_database {
         return null;
     }
 
+/// session lcoking
+    // http://download.oracle.com/docs/cd/B10501_01/appdev.920/a96612/d_lock2.htm#999576
+
 /// transactions
     /**
      * on DBs that support it, switch to transaction mode and begin a transaction