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CityHash is a family of non-cryptographic hash functions, designed for fast hashing of strings. It has 32-, 64-, 128-, and 256-bit variants. CityHash been referenced widely in academic papers. Google developed the algorithm in-house starting in 2010.〔https://code.google.com/p/cityhash/〕 The C++ source code for the reference implementation of the algorithm was released in 2011 under an MIT license, with credit to Geoff Pike and Jyrki Alakuijala.〔http://google-opensource.blogspot.com/2011/04/introducing-cityhash.html〕 The authors expect the algorithm to outperform previous work by a factor of 1.05 to 2.5, depending on the CPU and mix of string lengths being hashed.〔 CityHash is influenced by and partly based on MurmurHash.〔https://code.google.com/p/cityhash/source/browse/trunk/src/city.cc〕 Some particularly fast CityHash functions depend on CRC32 instructions that are present in SSE4.2. However, most CityHash functions are designed to be portable, though they will run best on little-endian 32-bit or 64-bit CPUs.〔https://code.google.com/p/cityhash/source/browse/trunk/README〕 Google has announced FarmHash as the successor to CityHash. == Concerns == CityHash releases do not maintain backward compatibility with previous versions.〔https://code.google.com/p/cityhash/source/browse/trunk/NEWS〕 Users should not use CityHash for persistent storage, or else not upgrade CityHash. The README warns that CityHash has not been tested much on big-endian platforms.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CityHash」の詳細全文を読む スポンサード リンク
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