MurmurHash

MurmurHash is a non-cryptographic hash function suitable for general hash-based lookup.^[1][2][3] It was created by Austin Appleby in 2008,^[4][5] and exists in a number of variants^[6], all of which have been released into the public domain.

Variants

The current version is MurmurHash3, which yields a 32-bit or 128-bit hash value and is optimized for Intel processors.

The older MurmurHash2 yields a 32-bit or 64-bit value. Slower versions of MurmurHash2 are available for big-endian and aligned-only machines. The MurmurHash2A variant adds the Merkle-Damgard construction so that it can be called incrementally. There are two variants which generate 64-bit values; MurmurHash64A, which is optimized for 64-bit processors, and MurmurHash64B, for 32-bit ones. MurmurHash2-160 generates the 160-bit hash, and MurmurHash1 is obsolete.

Implementations

The canonical implementations are in C++, but there are efficient ports for a variety of popular languages, including Python,^[7] C#,^[8] Perl,^[9] Ruby^[10], PHP^[11], Haskell,^[12] Java,^[13] and JavaScript.^[14][15]

It has been adopted into a number of open-source projects, most notably libstdc++ (ver 4.6), nginx (ver 1.0.1)^[16], libmemcached^[17] (the C driver for Memcached), maatkit,^[18], Hadoop.^[1], Kyoto Cabinet^[19], RaptorDB^[20] and Scala^[21].

References

1. ^ ^{a b} Hadoop in Java
2. ^ Chouza et al.
3. ^ Couceiro et al.
4. ^ MurmurHash on GooglePages
5. ^ MurmurHash first announcement
6. ^ MurmurHash2-160
7. ^ pyfasthash in Python
8. ^ Davy Landman in C#
9. ^ Toru Maesaka in Perl
10. ^ Ruby
11. ^ Murmurhash3 PHP extension
12. ^ Haskell
13. ^ Derek Young in Java, public domain
14. ^ Javascript implementation by Ray Morgan
15. ^ MurmurHash.js by Gary Court
16. ^ nginx
17. ^ libmemcached
18. ^ maatkit
19. ^ Kyoto Cabinet specification
20. ^ RaptorDB CodeProject page
21. ^ Scala compiler implementation

See also

• Fowler–Noll–Vo hash function
• Jenkins hash function