xxhash_64

description

Syntax

BIGINT XXHASH_64(VARCHAR input, ...)

返回输入字符串的64位xxhash值。

注：在计算hash值时，更推荐使用xxhash_64，而不是murmur_hash3_64。

example

  1. mysql> select xxhash_64(NULL);
  2. +-----------------+
  3. | xxhash_64(NULL) |
  4. +-----------------+
  5. |            NULL |
  6. +-----------------+
  8. mysql> select xxhash_64("hello");
  9. +----------------------+
  10. | xxhash_64('hello')   |
  11. +----------------------+
  12. | -7685981735718036227 |
  13. +----------------------+
  15. mysql> select xxhash_64("hello", "world");
  16. +-----------------------------+
  17. | xxhash_64('hello', 'world') |
  18. +-----------------------------+
  19. |         7001965798170371843 |
  20. +-----------------------------+

benchmark

通过TPCH Benchmark测试发现，xxhash_64相比murmur_hash3_64来说性能大幅提升，因此在需要计算hash值的场景下，更推荐使用xxhash_64。

  1. mysql> select count(murmur_hash3_64(l_comment)) from lineitem;
  2. +-----------------------------------+
  3. | count(murmur_hash3_64(l_comment)) |
  4. +-----------------------------------+
  5. |                         600037902 |
  6. +-----------------------------------+
  7. 1 row in set (17.18 sec)
  9. mysql> select count(xxhash_64(l_comment)) from lineitem;
  10. +-----------------------------+
  11. | count(xxhash_64(l_comment)) |
  12. +-----------------------------+
  13. |                   600037902 |
  14. +-----------------------------+
  15. 1 row in set (8.41 sec)

keywords

XXHASH_64,HASH