sub Compare
{
  my($k1, $k2)=@_;
  $k1 cmp $k2;
}

...

$DB_BTREE->{'compare'} = \&Compare ;


##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

use DB_File;

my %hash;

tie %hash, 'DB_File', undef, undef, 0666, $DB_BTREE;

$DB_BTREE->{'compare'} = sub {  my($k1, $k2)=@_;
  my($v1)=split(' , ', $hash{$k1});
  my($v2)=split(' , ', $hash{$k2});
  $v1 <=> $v2;
};

$hash{key1}='1 , First data';
$hash{key2}='2 , Second data';
$hash{key3}='3 , Third data';

print "A random record (#2): $hash{key2}\n";

#notice no sort on the next line as the records come back in order.
foreach my $k ( keys %hash )
{
  my($n, $v)=split(' , ', $hash{$k});
  print "$k: $n: $v\n";
}