The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Wednesday, November 14, 2007

Notes on a possible way to store tuples in a greylist implementation

I was checking some other greylist implementations when I came across an implementation that only stores a 32-bit hash instead of the full tuple. The idea sounded intriguing, and since I'm already calculating a 32-bit CRC as part of my protocol, I thought it might be interesting to see just how effective it might be.

Out of 499,846 unique tuples checked, only 28 had duplicate CRCs. I think I could live with that; I could then store 32× the number of tuples in the same amount of memory. Of course, I lose the ability to see the actual tuples, but for a huge ISP or webhosting company trying to deal with an insane amount of email, that is certainly a viable option (hint, hint—Rob, you listening?)

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