use File::SortedSeek;

sub record_search {
    my ($key, $filename, $recordsize) = @_;
    my $fh = IO::File->new($filename, 'r')
        or croak("Could not open $filename: $!");

    # I don't see any difference in speed with the next line
    # File::SortedSeek::set_line_length($recordsize);
    numeric( $fh, $key);
    return File::SortedSeek::was_exact();
}