CONFIG REWRITE

Available since 2.8.0.

CONFIG REWRITE命令用于重写redis server启动时使用的配置文件,以最小的变动反映当前server的实际配置,当前的实际配置可能会由于CONFIG SET的使用而与启动时的配置文件不同.

类似 scope=spfile

重写以非常保守的方式执行:

  • 尽可能保留原始redis.conf的注释和整体结构.
  • 如果一个选项已经存在于旧的redis.conf文件中,它将被原地更新.
  • 如果某个选项尚不存在,但设置为其默认值,则不会由重写过程添加.
  • 如果某个选项尚不存在,但它被设置为非默认值,则会将其附加到文件末尾.
  • Non used lines are blanked. For instance if you used to have multiple save directives, but the current configuration has fewer or none as you disabled RDB persistence, all the lines will be blanked.

    未使用的行将被删除.例如,如果您曾经设置多个save,但是后来却通过config set只设置了更少的或者config set save ‘’,那么所有的未使用save将被删除

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    [root@cn_mu_binlog_backup ~]# redis-cli -p 6379 config get save
    1) "save"
    2) ""
    [root@cn_mu_binlog_backup ~]# cat /usr/local/redis/etc/6379_redis.conf|grep save
    # save <seconds> <changes>
    # Will save the DB if both the given number of seconds and the given
    # In the example below the behaviour will be to save:
    # Note: you can disable saving completely by commenting out all "save" lines.
    # It is also possible to remove all the previously configured save
    # points by adding a save directive with a single empty string argument
    # save ""
    save 900 1
    save 300 10
    save 60 10000
    ...
    重写
    [root@cn_mu_binlog_backup ~]# redis-cli -p 6379 config rewrite
    OK
    [root@cn_mu_binlog_backup ~]# cat /usr/local/redis/etc/6379_redis.conf|grep save
    # save <seconds> <changes>
    # Will save the DB if both the given number of seconds and the given
    # In the example below the behaviour will be to save:
    # Note: you can disable saving completely by commenting out all "save" lines.
    # It is also possible to remove all the previously configured save
    # points by adding a save directive with a single empty string argument
    # save ""
    # (at least one save point) and the latest background save failed.
    stop-writes-on-bgsave-error yes
    # If you want to save some CPU in the saving child set it to 'no' but
    # algorithms (in order to save memory), so you can tune it for speed or
    # the configured save points).
    # saving process (a background save or AOF log background rewriting) is
    # Lists are also encoded in a special way to save a lot of space.
    # order to save a lot of space. This encoding is only used when the length and

如果由于某种原因原来的配置文件不再存在,CONFIG REWRITE也可以重写配置文件. 但是,如果服务器启动时没有配置文件,CONFIG REWRITE将只返回一个错误.

原子重写过程

In order to make sure the redis.conf file is always consistent, that is, on errors or crashes you always end with the old file, or the new one, the rewrite is performed with a single write(2) call that has enough content to be at least as big as the old file. Sometimes additional padding in the form of comments is added in order to make sure the resulting file is big enough, and later the file gets truncated to remove the padding at the end.

为了确保redis.conf文件始终保持一致,即在出现错误或崩溃时总是以旧文件或新文件结束,重写将使用具有足够内容的单次写入(2)调用来执行 至少与旧文件一样大. 有时会添加注释形式的其他填充以确保生成的文件足够大,然后文件被截断以删除最后的填充.

返回值

Simple string reply: OK 当配置被正确重写. 否则,返回错误

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