There is always the possibility that you could generate the numbers and create a checkssm that is significantly smaller than 16 digits.

Then you would only have to compare the checksums (and hold them in memory) for uniquness.

The only caveat being that in a list of 600,000,000 keys you, most likely, will have some codes/numbers which are unique but have the same checksum.

In reply to Re: Maintaining uniqueness across millions of items by ChuckularOne
in thread Maintaining uniqueness across millions of items by sdbarker

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