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什么是慢查询
和mysql的慢SQL日记说明一样，redis也有相同的成果，来辅佐定位一些慢查询操纵。
Redis slowlog是Redis用来记录查询执行时刻的日记体系。
查询执行时刻指的是不包罗像客户端相应(talking)、发送回覆等IO操纵，而单单是执行一个查询呼吁所淹灭的时刻。
其它，slow log生涯在内存内里，读写速率很是快，因此你可以安心地行使它，不必担忧由于开启slow log而侵害Redis的速率。
慢查询参数
起首来存眷下慢日记说明对应的两个参数：
1、slowlog-log-slower-than：预设阀值，即记录高出几多时刻的记录，默以为10000微秒，即10毫秒。
2、slowlog-max-len：记录慢查询的条数，默以为128条，当高出配置的条数时最早进入行列的将被移除。线上提议增大数值，如：1000，这样可镌汰行列移除的频率。
- 127.0.0.1:6379> config get slowlog-log-slower-than
- 1) "slowlog-log-slower-than"
- 2) "10000"
- 127.0.0.1:6379> config get slowlog-max-len
- 1) "slowlog-max-len"
- 2) "128"
可以用config set对这两个参数举办调解，可能在设置文件中配置。
- ################################## SLOW LOG ###################################
- # The Redis Slow Log is a system to log queries that exceeded a specified
- # execution time. The execution time does not include the I/O operations
- # like talking with the client, sending the reply and so forth,
- # but just the time needed to actually execute the command (this is the only
- # stage of command execution where the thread is blocked and can not serve
- # other requests in the meantime).
- #
- # You can configure the slow log with two parameters: one tells Redis
- # what is the execution time, in microseconds, to exceed in order for the
- # command to get logged, and the other parameter is the length of the
- # slow log. When a new command is logged the oldest one is removed from the
- # queue of logged commands.
- # The following time is expressed in microseconds, so 1000000 is equivalent
- # to one second. Note that a negative number disables the slow log, while
- # a value of zero forces the logging of every command.
- slowlog-log-slower-than 10000
- # There is no limit to this length. Just be aware that it will consume memory.
- # You can reclaim memory used by the slow log with SLOWLOG RESET.
- slowlog-max-len 128
慢查询呼吁
语法：slowlog subcommand [argument]
如，举办查询慢查询、获取慢查询记录的数目、重置慢查询日记等操纵：
- 192.168.10.38:9001> slowlog get
- (empty list or set)
- 192.168.10.38:9001> slowlog get 10
- (empty list or set)
- 192.168.10.38:9001> slowlog len
- (integer) 0
- 192.168.10.38:9001> slowlog reset
- OK
【编辑保举】
- 值得看｜30道Redis口试题，口试官能问的都被我找到了
- 怎样行使Redis构建轻量级微处事
- MySQL数据库怎样去掉数据库中一再记录？
- 怎样行使Redis做MySQL的缓存
- 阿里P8架构师谈：MySQL慢查询优化、索引优化、以及表等优化总结
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