I've managed to write a solution to this problem that works, of sorts, but its *very* slow, especially with large tables (25,000 rows+).

My code's below - any suggestions on how to improve the speed of this would be very much appreciated.

my @tmpHash;
my $lastKey = $keys[$#keys];
%{$tmpHash[$#keys]{$tblData{$lastKey}}} = %tblData;

if ($#keys >= 1)
    {
        for (my $n = $#keys - 1; $n >= 0; $n--)
            {
                %{$tmpHash[$n]{$tblData{$keys[$n]}}} = %{$tmpHash[$n+1
+]};
            }
    }

%tableData = (%tableData, %{$tmpHash[0]});
[download]

--Foxcub