How to use TransactionScope in SQLCLR without escalation in MSDTC

Many of our DAL codes use TransactionScope for transactions. This works fine, but there is a problem when I use this DAL code from the SQLCLR procedure. The transaction went to MSDTC, which I do not want.

The problem can be easily reproduced:

• CLR execution

  [SqlProcedure]
  public static void ClrWithScope(string cmdText)
  {
      /* escalates to MSDTC when a transaction is already open */
      using ( var scope = new TransactionScope())
      {
          using (var connection = new SqlConnection("context connection=true;"))
          {
              connection.Open();
              using (var cmd = new SqlCommand(cmdText, connection))
              {
                  SqlContext.Pipe.ExecuteAndSend(cmd);
              }
          }
          scope.Complete();
      }
  }
  
  [SqlProcedure]
  public static void ClrWithTrans(string cmdText)
  {
      /* works as expected (without MSDTC escalation ) */
      using (var connection = new SqlConnection("context connection=true;"))
      {
          connection.Open();
          using (var tx = connection.BeginTransaction())
          {
              using (var cmd = new SqlCommand(cmdText, connection, tx))
              {
                  SqlContext.Pipe.ExecuteAndSend(cmd);
                  tx.Commit();
              }
          }
      }
  }
  

• SQL script used to execute the CLR procedure

  BEGIN TRANSACTION
  
  exec dbo.ClrWithTrans "select * from sys.tables";
  exec dbo.ClrWithScope "select * from sys.tables"; /* <- DOES NOT WORK! */
  
  ROLLBACK TRANSACTION
  

• error

  Msg 6549, Level 16, State 1, Procedure ClrWithScope, Line 0
  A .NET Framework error occurred during execution of user defined routine or aggregate 'clrClrWithScope': 
  System.Transactions.TransactionAbortedException: Die Transaktion wurde abgebrochen. ---> System.Transactions.TransactionPromotionException: MSDTC on server 'BLABLA' is unavailable. ---> System.Data.SqlClient.SqlException: MSDTC on server 'BLABLA' is unavailable.
  System.Data.SqlClient.SqlException: 
     bei System.Data.SqlServer.Internal.StandardEventSink.HandleErrors()
     bei System.Data.SqlServer.Internal.ClrLevelContext.SuperiorTransaction.Promote()
  System.Transactions.TransactionPromotionException: 
     bei System.Data.SqlServer.Internal.ClrLevelContext.SuperiorTransaction.Promote()
     bei System.Transactions.TransactionStatePSPEOperation.PSPEPromote(InternalTransaction tx)
     bei System.Transactions.TransactionStateDelegatedBase.EnterState(InternalTransaction tx)
  System.Transactions.TransactionAbortedException: 
     bei System.Transactions.TransactionStateAborted.CreateAbortingClone(InternalTransaction tx)
     bei System.Transactions.DependentTransaction..ctor(IsolationLevel isoLevel, InternalTransaction internalTransaction, Boolean blocking)
     bei System.Transactions.Transaction.DependentClone(DependentCloneOption cloneOption)
     bei System.Transactions.TransactionScope.SetCurrent(Transaction newCurrent)
     bei System.Transactions.TransactionScope.PushScope()
     bei System.Transactions.TransactionScope..ctor(TransactionScopeOption scopeOption)
     bei Giag.Silo.Data.SqlClr.ClrWithScope(String cmdText)
  . User transaction, if any, will be rolled back.
  

WIHTOUT: BEGIN TRANSACTION statement, dbo.ClrWithScope call works fine. I believe that the transaction launched by SQLServer is not considered when connecting .Net Framework.

. , SqlTransaction TransactionScope , , . DAL ( ).

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