Fix regression of repo not registering prefixes for previously inserted data

Change-Id: I90e47def6219560cdadd281b8f65b16036aa0801
Refs: #4247
diff --git a/src/storage/storage.hpp b/src/storage/storage.hpp
index 146368f..d724eb1 100644
--- a/src/storage/storage.hpp
+++ b/src/storage/storage.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018, Regents of the University of California.
+ * Copyright (c) 2014-2019, Regents of the University of California.
  *
  * This file is part of NDN repo-ng (Next generation of NDN repository).
  * See AUTHORS.md for complete list of repo-ng authors and contributors.
@@ -82,6 +82,12 @@
   virtual std::shared_ptr<Data>
   find(const Name& name, bool exactMatch = false) = 0;
 
+   /**
+   *  @brief Enumerate each entry in database and call @p f with name of stored data
+   */
+  virtual void
+  forEach(const std::function<void(const Name&)>& f) = 0;
+
   /**
    *  @brief  return the size of database
    */