SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Identifier a.key
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier a
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier b
     TableJoin (children 1)
      Function isNotDistinctFrom (children 1)
       ExpressionList (children 2)
        Identifier a.key
        Identifier b.key
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier a.key
