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慢SQL查询 #19

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diaosichengxuyuan opened this issue Sep 6, 2020 · 0 comments

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diaosichengxuyuan commented Sep 6, 2020 •

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1.slow_query_log
这个参数设置为ON，可以捕获执行时间超过一定数值的SQL语句。

2.long_query_time
当SQL语句执行时间超过此数值时，就会被记录到日志中，建议设置为1或者更短。

3.slow_query_log_file
记录日志的文件名。

4.log_queries_not_using_indexes
这个参数设置为ON，可以捕获到所有未使用索引的SQL语句，尽管这个SQL语句有可能执行得挺快。

mysql cpu 100%
show processlist查看正在执行的语句是否索引失效导致全表扫描
slow_query_log_file中查看是否有慢查询

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