From 8b1531b98f0d40bcd13edad89de8f7fb2cac0871 Mon Sep 17 00:00:00 2001
From: Wan Shen Lim <wanshenl@andrew.cmu.edu>
Date: Mon, 11 Jun 2018 14:51:58 -0400
Subject: [PATCH] treat txn w/ no modifying queries as read-only (#1396:4)

---
 .../timestamp_ordering_transaction_manager.cpp           | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/concurrency/timestamp_ordering_transaction_manager.cpp b/src/concurrency/timestamp_ordering_transaction_manager.cpp
index f3886ce9c4e..d3ece6e2cb9 100644
--- a/src/concurrency/timestamp_ordering_transaction_manager.cpp
+++ b/src/concurrency/timestamp_ordering_transaction_manager.cpp
@@ -623,6 +623,14 @@ ResultType TimestampOrderingTransactionManager::CommitTransaction(
   //// handle other isolation levels
   //////////////////////////////////////////////////////////
 
+  auto &rw_set = current_txn->GetReadWriteSet();
+
+  // if no modifying queries, treat as read-only
+  if (rw_set.empty()) {
+    EndTransaction(current_txn);
+    return ResultType::SUCCESS;
+  }
+
   auto storage_manager = storage::StorageManager::GetInstance();
   auto &log_manager = logging::LogManager::GetInstance();
 
@@ -631,7 +639,6 @@ ResultType TimestampOrderingTransactionManager::CommitTransaction(
   // generate transaction id.
   cid_t end_commit_id = current_txn->GetCommitId();
 
-  auto &rw_set = current_txn->GetReadWriteSet();
   auto &rw_object_set = current_txn->GetCreateDropSet();
 
   auto gc_set = current_txn->GetGCSetPtr();