How about this for single-level hashes: 
my @array_1 = sort keys( %hash_1);
my $key_string_1 = join('', @array_1);
my @array_2 = sort keys( %hash_2);
my $key_string_2 = join('', @array_2);
if ($key_string_1 eq $key_string_2) {
...

[download]
and you've got your strings of keys already.

In reply to Re: Fastest data structure compare? by punch_card_don
in thread Fastest data structure compare? by swartz

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