About memcached common commands and usage instructions

jacklove
Release: 2023-03-31 14:00:02
Original
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memcached View method

Format: telnet ip port

For example telnet localhost 11211
Exit command:quit

1. Storage command

Storage command Format:

<command name> <key> <flag> <expire> <bytes>
<data block>
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Parameter description:

command name Command name
keyFind keyword
flagStoring additional information
expireData storage time, 0 means forever, unit seconds
bytesThe number of bytes of stored data
data blockThe stored data

1.set 无论如何都存储,数据不存在时存储,数据存在时更新。

set mykey 0 0 3
123
STORED
set mykey 0 0 3
456
STORED
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2.add 当数据不存在时存储。

add mykey 0 0 3
123
STORED
add mykey 0 0 3
456
NOT_STORED
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3.replace 当数据存在时存储

set mykey 0 0 3
123
STORED
replace mykey 0 0 3
456
STORED
delete mykey
DELETED
replace mykey 0 0 3
678
NOT_STORED
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二.读取命令

1.get key 可以一个或多个,用空格格开。

set mykey 0 0 3
123
STORED
set mykey1 0 0 3
456
STORED
get mykey mykey1
VALUE mykey 0 3
123
VALUE mykey1 0 3
456
END
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2.gets 与 get 一样,但会返回多一个数字,这个数字用来检查数据是否被修改过,如修改过,这个数字回改变。

set mykey 0 0 3
123
STORED
gets mykey
VALUE mykey 0 3 7
123
END
replace mykey 0 0 3
888
STORED
gets mykey
VALUE mykey 0 3 8
888
END
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3.cas cas即checked and set ,当最后一个参数与gets返回的数字一致时才存储,否则返回EXISTS。

set mykey 0 0 3
123
STORED
gets mykey
VALUE mykey 0 3 9
123
END
cas mykey 0 0 3 8
456
EXISTS
cas mykey 0 0 3 9
456
STORED
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三.追加与清除命令

1.append 将数据追加到当前缓存数据的之后,当缓存数据存在时才存储。

set mykey 0 0 3
123
STORED
append mykey 0 0 3
456
STORED
get mykey
VALUE mykey 0 6
123456
END
append notexists 0 0 3
456
NOT_STORED
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2.prepend 将数据追加到当前缓存数据的之前,当缓存数据存在时才存储。

set mykey 0 0 3
123
STORED
prepend mykey 0 0 3
456
STORED
get mykey
VALUE mykey 0 6
456123
END
prepend notexists 0 0 3
456
NOT_STORED
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3.delete 删除缓存数据,数据存在返回DELETED,数据不存在返回NOT_FOUND

set mykey 0 0 3
123
STORED
delete mykey
DELETED
delete mykey
NOT_FOUND
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4.flush_all 将当前所有缓存数据设置为过期,但不会释放内存。

flush_all
OK
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四.状态命令

1.stats 查看memcached运行状态

pid                     Memcached 进程ID  
  
uptime                  Memcached 运行时间,单位:秒  
  
time                    Memcached 当前的UNIX时间  
  
version                 Memcached 的版本号  
  
rusage_user             该进程累计的用户时间,单位:秒  
  
rusage_system           该进程累计的系统时间,单位:秒  
  
curr_items              Memcached 当前存储的内容数量  
  
total_items             Memcached 启动以来存储过的内容总数  
  
bytes                   Memcached 当前存储内容所占用的字节数(*/1024/1024=mb)  
  
curr_connections        当前连接数量  
  
total_connections       Memcached 运行以来接受的连接总数  
  
connection_structures   Memcached 分配的连接结构的数量  
  
cmd_get                 查询请求总数  
  
cmd_set                 存储(添加/更新)请求总数  
  
get_hits                查询成功获取数据的总次数  
  
get_misses              查询成功未获取到数据的总次数  
  
bytes_read              Memcached 从网络读取到的总字节数  
  
bytes_written           Memcached 向网络发送的总字节数  
  
limit_maxbytes          Memcached 在存储时被允许使用的字节总数
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2.stats items
执行stats items,可以看到STAT items行,如果memcached存储内容很多,那么这里也会列出很多的STAT items行。

3.stats cachedump slabs_id limit_num
slabs_id:由stats items返回的结果(STAT items后面的数字)决定的
limit_num:返回的记录数,0表示返回所有记录
通过stats items、stats cachedump slab_id limit_num配合get命令可以遍历memcached的记录。

stats cachedump 1 0
ITEM mykey [3 b; 1362880145 s]
END
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4.stats slabs 显示各个slab的信息,包括chunk的大小、数目、使用情况等


5.stats sizes
 输出所有item的大小和个数


6.stats reset
清空统计数据

本文讲解了memcached 常用命令及使用说明,更多相关内容请关注php中文网。

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