SERVER-45405 Allow implicit collection creation inside multi-doc txns

3 files changed, 10 insertions, 9 deletions

diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 14d57c18b74..8150dfbeb70 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -1427,11 +1427,8 @@ Status applyCommand_inlock(OperationContext* opCtx,
 
         switch (replMode) {
             case ReplicationCoordinator::modeReplSet: {
-                // The 'applyOps' command never logs 'applyOps' oplog entries with nested
-                // command operations, so this code will never be run from inside the 'applyOps'
-                // command on secondaries. Thus, the timestamps in the command oplog
-                // entries are always real timestamps from this oplog and we should
-                // timestamp our writes with them.
+                // The timestamps in the command oplog entries are always real timestamps from this
+                // oplog and we should timestamp our writes with them.
                 return true;
             }
             case ReplicationCoordinator::modeNone: {
diff --git a/src/mongo/db/repl/rollback_impl.cpp b/src/mongo/db/repl/rollback_impl.cpp
index aa5d60beb85..26c9c1a0fd4 100644
--- a/src/mongo/db/repl/rollback_impl.cpp
+++ b/src/mongo/db/repl/rollback_impl.cpp
@@ -946,9 +946,11 @@ Status RollbackImpl::_processRollbackOpForApplyOps(OperationContext* opCtx,
     invariant(oplogEntry.getCommandType() == OplogEntry::CommandType::kApplyOps);
 
     try {
+        // Roll back operations in reverse order in order to account for non-commutative
+        // members of applyOps (e.g., commands inside of multi-document transactions).
         auto subOps = ApplyOps::extractOperations(oplogEntry);
-        for (auto& subOp : subOps) {
-            auto subStatus = _processRollbackOp(opCtx, subOp);
+        for (auto reverseIt = subOps.rbegin(); reverseIt != subOps.rend(); ++reverseIt) {
+            auto subStatus = _processRollbackOp(opCtx, *reverseIt);
             if (!subStatus.isOK()) {
                 return subStatus;
             }
diff --git a/src/mongo/db/repl/transaction_oplog_application.cpp b/src/mongo/db/repl/transaction_oplog_application.cpp
index 3d2f77905dc..99185e45c14 100644
--- a/src/mongo/db/repl/transaction_oplog_application.cpp
+++ b/src/mongo/db/repl/transaction_oplog_application.cpp
@@ -65,9 +65,11 @@ Status _applyOperationsForTransaction(OperationContext* opCtx,
     // Apply each the operations via repl::applyOperation.
     for (const auto& op : ops) {
         try {
-            Status status = Status::OK();
+            // Presently, it is not allowed to run a prepared transaction with a command
+            // inside. TODO(SERVER-46105)
+            invariant(!op.isCommand());
             AutoGetCollection coll(opCtx, op.getNss(), MODE_IX);
-            status = repl::applyOperation_inlock(
+            auto status = repl::applyOperation_inlock(
                 opCtx, coll.getDb(), &op, false /*alwaysUpsert*/, oplogApplicationMode);
             if (!status.isOK()) {
                 return status;