#!/usr/bin/perl

use strict;
use warnings;
use DBI ();

traverse_tree($ARGV[0]);

exit;

sub traverse_tree {
    my $root_id=shift;
    my $dbh=DBI->connect('dbi:Pg:dbname=test');
    my $sql = 'SELECT tt.node_level,tt.node_id,tree.name'
            . ' FROM traverse_tree(?) tt JOIN tree ON node_id=tree.id';
    my $sth=$dbh->prepare($sql);
    $sth->execute($root_id);
    while ( my $node = $sth->fetchrow_hashref() ) {
      print $node->{'node_id'},
        " ",
        "  " x $node->{'node_level'},
        $node->{'name'},
        "\n";
    }
}