CreateQuery group_by_null_key (children 3)
 Identifier group_by_null_key
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration c1 (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType Int32
   ColumnDeclaration c2 (children 1)
    DataType LowCardinality (children 1)
     ExpressionList (children 1)
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType Int32
 Storage definition (children 1)
  Function Memory (children 1)
   ExpressionList
