my %data_hash;

foreach $elem (@data) {
    my ($sub, $max) = split /\|/, $elem;
    $data_hash{$sub} = $max;
}

foreach $r (@ref) {
    my ($id, $time) =      split /\|/, $r;
    my ($key, $instance) = split /:/, $id;
    if ($data_hash{$key} ne $time) {
        push @set, join (':', $key, $instance);
    }
}