MySQL Troubleshooting

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• Maintenance Tools 1. Tools from the MySQL distribution 2. Percona Toolkit 3. MySQL WB Utilities 4. Monitoring tools (查看原文)

  员外👻 1赞 2012-03-03 12:48:07

• What jumps out is the high value of Handler_read_rnd_next, which shows how often the next row in a datafile was read. A high value typically means that a table scan was used, which is not good for performance. Handler_read_key is a related variable showing the number of index read requests. It shouldn’t be so low in relation to Handler_read_rnd_next, because that means a lot of rows were read instead of using an index. In addition, the values of Handler_commit and Handler_read_first have increased slightly. These refer respectively to the number of commits and the number of times the first entry in an index was read. Finally, the unobtrusive 1 in Handler_read_first shows that we asked the server to read a first entry in the index, which can be a symptom of a full index scan. (查看原文)

  员外👻 2012-03-02 20:28:19

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