Design of a near-minimal dynamic perfect hash function on embedded device

There has been a general opinion that it is difficult to construct perfect hash tables with high load factor for large datasets having a million records. The problem is even more challenging if new records can be added to the hash table incrementally. In this article, we shall demonstrate the design of a dynamic perfect hash function on embedded device based on simple bit-shuffle and bit-extraction operations. The achievable load factor can be up to 100%, and the amortized memory cost of the hash function is about 7 to 15 bits per key for 32-bit keys. Incremental updates to the hash table are allowed. The perfect hash function for a dataset with 1 million keys can be constructed in a few seconds of CPU time.