diff --git a/src/sync-core.cc b/src/sync-core.cc
index c325eb1..d90c463 100644
--- a/src/sync-core.cc
+++ b/src/sync-core.cc
@@ -288,7 +288,10 @@
   m_rootHash = m_log.RememberStateInStateLog();
   SyncStateMsgPtr diff = m_log.FindStateDifferences(*oldHash, *m_rootHash);
 
-  m_stateMsgCallback(diff);
+  if (diff->state_size() > 0)
+  {
+    m_stateMsgCallback(diff);
+  }
 }
 
 void
@@ -345,3 +348,9 @@
   bytes.resize(size);
   msg->SerializeToArray(head(bytes), size);
 }
+
+sqlite3_int64
+SyncCore::seq(const Name &name)
+{
+  return m_log.SeqNo(name);
+}
diff --git a/src/sync-core.h b/src/sync-core.h
index 998be7d..d8c9675 100644
--- a/src/sync-core.h
+++ b/src/sync-core.h
@@ -86,9 +86,13 @@
   void
   recover(const HashPtr &hash);
 
+// ------------------ only used in test -------------------------
   HashPtr
   root() { return m_rootHash; }
 
+  sqlite3_int64
+  seq(const Name &name);
+
 protected:
   void
   sendSyncInterest();
diff --git a/src/sync-log.cc b/src/sync-log.cc
index c9f125a..8375142 100644
--- a/src/sync-log.cc
+++ b/src/sync-log.cc
@@ -34,6 +34,7 @@
   cout << q << endl;
 }
 
+
 SyncLog::SyncLog (const boost::filesystem::path &path, const std::string &localName)
   : DbHelper (path)
   , m_localName (localName)
@@ -399,3 +400,19 @@
 
   return msg;
 }
+
+sqlite3_int64
+SyncLog::SeqNo(const Name &name)
+{
+  sqlite3_stmt *stmt;
+  sqlite3_int64 seq = -1;
+  sqlite3_prepare_v2 (m_db, "SELECT seq_no FROM SyncNodes WHERE device_name=?;", -1, &stmt, 0);
+  Ccnx::CcnxCharbufPtr nameBuf = name;
+  sqlite3_bind_blob (stmt, 1, nameBuf->buf (), nameBuf->length (), SQLITE_STATIC);
+  if (sqlite3_step (stmt) == SQLITE_ROW)
+  {
+    seq = sqlite3_column_int64 (stmt, 0);
+  }
+
+  return seq;
+}
diff --git a/src/sync-log.h b/src/sync-log.h
index 3ab8489..0a59516 100644
--- a/src/sync-log.h
+++ b/src/sync-log.h
@@ -74,6 +74,10 @@
   SyncStateMsgPtr
   FindStateDifferences (const Hash &oldHash, const Hash &newHash);  
 
+  //-------- only used in test -----------------
+  sqlite3_int64
+  SeqNo(const Ccnx::Name &name);
+
 protected:
   void
   UpdateDeviceSeqNo (sqlite3_int64 deviceId, sqlite3_int64 seqNo);