SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 3)
    Identifier y
    Identifier y.b.first
    Identifier y.b.second
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
    TablesInSelectQueryElement (children 1)
     ArrayJoin (children 1)
      ExpressionList (children 1)
       Identifier x (alias y)
