//Execute is what actually returns a value? Plan is executed which return a scan.
 protected override object InternalExecute(Program program, PlanNode planNode)
 {
     if (planNode is BaseTableVarNode)
     {
         FastoreCursor scan = new FastoreCursor(program, _db, (BaseTableVarNode)planNode);
         try
         {
             scan.Open();
             return(scan);
         }
         catch
         {
             scan.Dispose();
             throw;
         }
     }
     else if (planNode is OrderNode)
     {
         OrderNode orderNode = (OrderNode)planNode;
         if (orderNode.Order.Columns.Count == 1)
         {
             FastoreCursor scan = new FastoreCursor(program, _db, (BaseTableVarNode)planNode.Nodes[0]);
             try
             {
                 scan.Key        = orderNode.PhysicalOrder;
                 scan.Direction  = orderNode.ScanDirection;
                 scan.Node.Order = orderNode.Order;
                 scan.Open();
                 return(scan);
             }
             catch
             {
                 scan.Dispose();
                 throw;
             }
         }
         else
         {
             FastoreStackedCursor scan = new FastoreStackedCursor(program, _db, orderNode.Order, orderNode.PhysicalOrder, (BaseTableVarNode)planNode.Nodes[0]);
             try
             {
                 scan.Open();
                 return(scan);
             }
             catch
             {
                 scan.Dispose();
                 throw;
             }
         }
     }
     else if (planNode is CreateTableVarBaseNode)
     {
         EnsureFastoreTable(((CreateTableVarBaseNode)planNode).GetTableVar());
         return(null);
     }
     else if (planNode is AlterTableNode)
     {
         // TODO: Memory device alter table support
         return(null);
     }
     else if (planNode is DropTableNode)
     {
         Schema.TableVar tableVar = ((DropTableNode)planNode).Table;
         FastoreTables   tables   = GetTables(tableVar.Scope);
         lock (tables)
         {
             int tableIndex = tables.IndexOf(tableVar);
             if (tableIndex >= 0)
             {
                 FastoreTable nativeTable = tables[tableIndex];
                 nativeTable.Drop(program.ValueManager);
                 tables.RemoveAt(tableIndex);
             }
         }
         return(null);
     }
     else
     {
         throw new DeviceException(DeviceException.Codes.InvalidExecuteRequest, Device.Name, planNode.ToString());
     }
 }