SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function dumpColumnStructure (children 1)
     ExpressionList (children 1)
      Function materialize (children 1)
       ExpressionList (children 1)
        Identifier arr1
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier sparse_t