CreateQuery null_in_tuple (children 3)
 Identifier null_in_tuple
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration dt (children 1)
    DataType DateTime
   ColumnDeclaration idx (children 1)
    DataType int
   ColumnDeclaration t (children 1)
    DataType Tuple (children 1)
     ExpressionList (children 2)
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType UInt64
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType String
 Storage definition (children 4)
  Function MergeTree (children 1)
   ExpressionList
  Identifier dt
  Identifier idx
  Set
