my $twig = new XML::Twig ( TwigRoots, pretty_print => 'indented',
                              => { 'tables/table'    => \&processColumns,
                                   'views/view'    => \&processColumns } );
$twig->parsefile($SCHEMAS);
$twig->dispose;

sub processColumns {
   my( $twig, $tableTwig) = @_;

   my @colList = $tableTwig->find_nodes( "columns/column");
   foreach $x ( @colList){
      blah;
   }
   $twig->flush;
}