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This article shows you the order of the results of MySQL Cluster, which is concise and easy to understand, which will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

Recently, we set up the environment of MySQL Cluster to learn, and found a very interesting phenomenon. Without adding order by, the order of the returned results is random, and each time is different, as follows.

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Mysql > select * from test_ndb limit 3

+-+ +

| | I | a |

+-+ +

| | 5 | test5 |

| | 1 | test1 |

| | 2 | test2 |

+-+ +

3 rows in set (0.05sec)

Mysql > select * from test_ndb limit 3

+-+ +

| | I | a |

+-+ +

| | 7 | test7 |

| | 3 | test3 |

| | 6 | test6 |

+-+ +

3 rows in set (0.03 sec)

Mysql > select * from test_ndb limit 3

+-+ +

| | I | a |

+-+ +

| | 5 | test5 |

| | 1 | test1 |

| | 2 | test2 |

+-+ +

3 rows in set (0.05sec)

I think this should be related to the storage mode of NDB. NDB actually distributes the data of the table to different nodes using the hash algorithm. The primary key of the NDB table is not a clustered index like InnoDB, but a hash index, so the order of fetching the data each time is not necessarily the same.

The above is the order of the results of MySQL Cluster. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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