Bloom filters may be of use; you will need to check all positive answers in some other way (or rely on probabilities), but they may speed up the process.

A CPAN search yields several implementations, yet I am not familiar with any of them.

In reply to Re: Best way to look-up a string amongst 100 million of its peers by akho
in thread Best way to look-up a string amongst 100 million of its peers by anson

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