diff --git a/src/executor/populate_index_executor.cpp b/src/executor/populate_index_executor.cpp
index b6a282480bc..0d1aadbfc78 100644
--- a/src/executor/populate_index_executor.cpp
+++ b/src/executor/populate_index_executor.cpp
@@ -19,6 +19,7 @@
 #include "expression/tuple_value_expression.h"
 #include "storage/data_table.h"
 #include "storage/tile.h"
+#include "concurrency/lock_manager.h"
 
 namespace peloton {
 namespace executor {
@@ -54,7 +55,17 @@ bool PopulateIndexExecutor::DExecute() {
   auto current_txn = executor_context_->GetTransaction();
   auto executor_pool = executor_context_->GetPool();
   if (done_ == false) {
+    oid_t table_oid = target_table_->GetOid();
     //Get the output from seq_scan
+    concurrency::LockManager *lm = concurrency::LockManager::GetInstance();
+    bool lock_success = lm->LockExclusive(table_oid);
+    concurrency::LockManager::SafeLock dummy;
+    if (!lock_success) {
+      LOG_TRACE("Cannot obtain lock for the table, abort!");
+    }
+    else{
+      dummy.Set(table_oid, concurrency::LockManager::SafeLock::EXCLUSIVE);
+    }
     while (children_[0]->Execute()) {
       child_tiles_.emplace_back(children_[0]->GetOutput());
     }
diff --git a/src/include/concurrency/lock_manager.h b/src/include/concurrency/lock_manager.h
index 620aa80b2d8..71a24fee180 100644
--- a/src/include/concurrency/lock_manager.h
+++ b/src/include/concurrency/lock_manager.h
@@ -30,11 +30,19 @@ namespace concurrency {
 class LockManager {
  public:
 
+  //===--------------------------------------------------------------------===//
+  // Safe lock
+  //===--------------------------------------------------------------------===//
+  // Initial one of these after initialed lock on oid
+  // Remember to initial it as local variable
+  // It will automatically unlock the corresponding lock when the current scope
+  // exits (since the unlock logic is in its destructor).
   class SafeLock {
    public:
     // Type of locked read write locks.
     enum RWLockType { SHARED, EXCLUSIVE, INVALID };
 
+    // Default Constructor
     SafeLock(){
       oid_ = INVALID_OID;
       type_ = RWLockType::INVALID;
@@ -45,11 +53,13 @@ class LockManager {
       type_ = type;
     }
 
+    // Set the oid and type for the lock
     void Set(oid_t oid, RWLockType type){
       oid_ = oid;
       type_ = type;
     }
 
+    // Unlock the given lock in the constructor
     ~SafeLock(){
       LockManager *lm = LockManager::GetInstance();
       if (type_ == RWLockType::EXCLUSIVE){
@@ -60,6 +70,7 @@ class LockManager {
       }
     }
 
+   // Members
    private:
     oid_t oid_;
     RWLockType type_;
@@ -117,6 +128,7 @@ class LockManager {
   boost::upgrade_mutex internal_rw_lock_;
 
   // Map to store RW_LOCK for different objects
+  // Changed to shared_ptr for safety reasons
   std::map<oid_t, std::shared_ptr<boost::upgrade_mutex> > lock_map_;
 
   // Get RW lock by oid
diff --git a/test/sql/update_secondary_index_sql_test.cpp b/test/sql/update_secondary_index_sql_test.cpp
index 842bc1ca9ee..491b7c90a08 100644
--- a/test/sql/update_secondary_index_sql_test.cpp
+++ b/test/sql/update_secondary_index_sql_test.cpp
@@ -67,6 +67,13 @@ TEST_F(UpdateSecondaryIndexSQLTests, UpdateSecondaryIndexTest) {
   // Check the return value
   EXPECT_EQ(result[0][0], '2');
 
+  // test update result, see if original entry not accessible
+  TestingSQLUtil::ExecuteSQLQuery("SELECT * FROM test WHERE b=20", result,
+                                  tuple_descriptor, rows_affected,
+                                  error_message);
+  // Check the return value
+  EXPECT_EQ(result.size(), 0);
+
   // free the database just created
   txn = txn_manager.BeginTransaction();
   catalog::Catalog::GetInstance()->DropDatabaseWithName(DEFAULT_DB_NAME, txn);