After completing P4's MVCC in Fall 2024, I submitted P3. It passed locally but failed on Gradescope.

[widsnoy]

Hello! Has anyone submitted P3 after completing MVCC for project4? I passed all SQL test cases in local release mode, but it failed on Gradescope. From printf observations, it seems BusTubInstance::ExecuteSql never commits the transaction, as ReadTs is always 0, and the tuple's ts for insert transactions is still the value before commit.

I commented out the transaction commit code in bustub_instance.cpp locally, and I got the same result as Gradescope: when I select * from table, I don't see the tuples inserted by previous transactions because they haven't been committed.

if (!is_local_txn) {
  std::cout << "Commit txn\n";
  auto res = txn_manager_->Commit(txn);
  if (!res) {
    throw Exception("failed to commit txn");
  }
}

However, I can't modify or view Gradescope's code. Does this mean I can only delete the MVCC part of the code to continue with the extra tasks for P3?

Gradescope's log:

68: <main>:4
68: create table t1(v1 int, v2 varchar(128), v3 int);
68: ----
68: Table created with id = 29	
68: 
68: <main>:8
68: insert into t1 values (0, '🥰', 10), (1, '🥰🥰', 11), (2, '🥰🥰🥰', 12), (3, '🥰🥰🥰🥰', 13), (4, '🥰🥰🥰🥰🥰', 14);
68: --- YOUR RESULT ---
68: 5 
68: 
68: --- EXPECTED RESULT ---
68: 5
68: 

[TxnMgrDbg]:
68: debug_hook: 233
68: <main>:13
68: select * from t1;
68: RID14/0 ts=txn3 tuple=(0, 🥰, 10)
68: RID14/1 ts=txn3 tuple=(1, 🥰🥰, 11)
68: RID14/2 ts=txn3 tuple=(2, 🥰🥰🥰, 12)
68: RID14/3 ts=txn3 tuple=(3, 🥰🥰🥰🥰, 13)
68: RID14/4 ts=txn3 tuple=(4, 🥰🥰🥰🥰🥰, 14)

68: [CollectUndologs]:
68: current_txn_read_ts = 0 base_tuple_ts = 4611686018427387907
68: current_txn_ts = 4611686018427387908

...

68: --- YOUR RESULT ---
68: 
68: --- EXPECTED RESULT ---
68: 0 🥰 10
68: 1 🥰🥰 11
68: 2 🥰🥰🥰 12
68: 3 🥰🥰🥰🥰 13
68: 4 🥰🥰🥰🥰🥰 14

[widsnoy]

I found the cause of the problem: P3_FILES doesn't include transaction_manager.cpp, so the timestamp of the tuples modified by the transaction wasn't updated upon commit...