More Robust Hashing: Cuckoo Hashing with a Stash

Cuckoo hashing holds great potential as a high-performance hashing scheme for real

applications. Up to this point, the greatest drawback of cuckoo hashing appears to be that there is a polynomially small but practically significant probability that a failure will occur during the insertion of an item, requiring an expensive rehashing of all items in the table. In this paper, we show that this failure probability can be dramatically reduced by the addition of a very small constant-sized stash. We demonstrate both analytically and through simulations that stashes of size equivalent to only three or four items yield tremendous improvements, enhancing cuckoo hashing’s practical viability in both hardware and software. Our analysis naturally extends previous analyses of multiple cuckoo hashing variants, and the approach may prove useful in further related schemes.

In  Siam Journal Computing

Publisher  Society for Industrial and Applied Mathematics
Copyright © 2007 by Society for Industrial and Applied Mathematics.

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