# a unique SessionID for the query already available 
# in package global $session

my $cache_file = $session.'_cache.yaml';
my $result_set;

if (-f $cache_file && -r $cache_file && -s $cache_file) {
    # we already ran this query (session), and we have a cache!
    $result_set = YAML::LoadFile($cache_file);
}
else {
    $result_set->{data}  = run_dbQuery();
    $result_set->{start} = 0;
}

display_results( $result_set->{data}, $result_set->{start}, 20 );
$result_set->{start} += 20;

YAML::DumpFile($cache_file, $result_set);

#---- display_results : shows slice of result set ----
sub display_results {
   my ( $data, $start, $length ) = @_;
   die "Data Set is not an ARRAY ref" unless ref $data eq 'ARRAY';

   my $endpoint = ( $start+$length > @$data ? @$data-1 : $start+$length-1 );
   show_toBrowser( @$data[$start..$endpoint] );
}