The previous answer about an embedded database was appropriate, however, a HoA structure might also be appropriate if you don't need persistence. I just built one, so here it is: Hash has UNIX commands as keys. For each hash key, I save an anonymous array of two cells (recent history, and popularity) as value. I then need to sort that hash based on one or the other.

read a file line into $line, then:
  my @arry = split(/==/, $line); #recent==pop==commandname
  $myhash{$arry[$#arry]} = [$arry[0], $arry[1]];
loop until done

to sort:

    my @recentkeys = sort by_HoA_0_asc keys(%myhash);
    my @popkeys = sort by_HoA_1_desc keys(%myhash);

# sort Hash of Arrays by numeric value of first 
# array value(history), ascending

sub by_HoA_0_asc
{
    if ($myhash{$a}[0] < $myhash{$b}[0]) 
    { 
    return -1; 
    }
    elsif ($myhash{$a}[0] > $myhash{$b}[0])
    {
    return 1;
    }
    return 0;
}

# sort Hash of Arrays by numeric value of second 
# array value (popularity), descending. If equal, 
# sort by first array value (history), ascending.

sub by_HoA_1_desc
{
    if ($myhash{$a}[1] > $myhash{$b}[1]) 
    { 
    return -1; 
    }
    elsif ($myhash{$a}[1] < $myhash{$b}[1])
    {
    return 1;
    }
    if ($myhash{$a}[0] < $myhash{$b}[0])
    {
    return -1;
    }
    elsif ($myhash{$a}[0] < $myhash{$b}[0])
    {
    return 1;
    }
    return 0;
}
[download]