CreateQuery test_group_by_with_rollup_order (children 3)
 Identifier test_group_by_with_rollup_order
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration id (children 1)
    DataType Int64
   ColumnDeclaration a (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType Int64
   ColumnDeclaration b (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType String
 Storage definition (children 2)
  Function MergeTree
  Identifier id
