详解redis-cli 命令 - 主机乐 - 做有意思的尝试

root@hylaz:~# redis-cli
127.0.0.1:6379> set name hylaz
OK
127.0.0.1:6379> quit
root@hylaz:~# redis-cli -h 127.0.0.1
127.0.0.1:6379> get name
“hylaz”
127.0.0.1:6379> select 6
127.0.0.1:6379[6]>

root@hylaz:~# redis-cli -h 127.0.0.1 -p 6379 -n 2
127.0.0.1:6379[2]> get age

server中统计选项

root@hylaz:~# redis-cli –stat
——- data —— ——————— load ——————– – child –
keys memclients blocked requestsconnections
11 835.52K1 0 12 (+0) 5
11 835.52K1 0 13 (+1) 5
11 835.52K1 0 14 (+1) 5
11 835.52K1 0 15 (+1) 5

列表中选项说明：

选项	含义
keys	server中key的数量
mem	键值对的总内存量
clients	当前连接的总clients数量
blocked	当前阻塞的客户端数量
requests	服务器请求总次数 (+1) 截止上次请求增加次数
connections	服务器连接次数

使用info命令获取服务器的信息

导入rdb文件　命令：redis-cli –rdb rdb.log

root@hylaz:~# redis-cli –rdb rdb.log
SYNC sent to master, writing 344 bytes to ‘rdb.log’
Transfer finished with success.

该命令选项实现：

向server发送SYNC命令，返回需要写的总字节数
从server读取总字节数据写到指定文件中

找出各种数据类型的最大键值对　

命令：redis-cli –big-keys

root@hylaz:~# redis-cli –bigkeys

# Scanning the entire keyspace to find biggest keys as well as
# average sizes per key type.You can use -i 0.1 to sleep 0.1 sec
# per 100 SCAN commands (not usually needed).

[00.00%] Biggest string found so far ‘name1’ with 5 bytes
[00.00%] Biggest setfound so far ‘myset’ with 1 members
[00.00%] Biggest string found so far ‘key’ with 6 bytes

——– summary ——-

Sampled 13 keys in the keyspace!
Total key length in bytes is 52 (avg len 4.00)

Biggest string found ‘key’ has 6 bytes
Biggestset found ‘myset’ has 1 members

12 strings with 33 bytes (92.31% of keys, avg size 2.75)
0 lists with 0 items (00.00% of keys, avg size 0.00)
1 sets with 1 members (07.69% of keys, avg size 1.00)
0 hashs with 0 fields (00.00% of keys, avg size 0.00)
0 zsets with 0 members (00.00% of keys, avg size 0.00)
0 streams with 0 entries (00.00% of keys, avg size 0.00)

该选项实现：通过使用scan命令遍历server中的键值对，针对不同数据类型进行统计，

找出server中热点key 命令：redis-cli –hotkeys

# Scanning the entire keyspace to find hot keys as well as
# average sizes per key type.You can use -i 0.1 to sleep 0.1 sec
# per 100 SCAN commands (not usually needed).

[00.00%] Hot key ‘dd’ found so far with counter 4
[00.00%] Hot key ‘myset’ found so far with counter 5
[00.00%] Hot key ‘a’ found so far with counter 5
[00.00%] Hot key ‘dds’ found so far with counter 4
[71.43%] Hot key ‘aa’ found so far with counter 4
[71.43%] Hot key ‘key’ found so far with counter 4

——– summary ——-

Sampled 14 keys in the keyspace!
hot key found with counter: 5keyname: myset
hot key found with counter: 5keyname: a
hot key found with counter: 4keyname: dd
hot key found with counter: 4keyname: dds
hot key found with counter: 4keyname: aa
hot key found with counter: 4keyname: key

选项实现：

1. redis实现8种缓存淘汰策略：

voltile-lru：从已设置过期时间的数据集（server.db[i].expires）中挑选最近最少使用的数据淘汰

volatile-ttl：从已设置过期时间的数据集（server.db[i].expires）中挑选将要过期的数据淘汰

volatile-random：从已设置过期时间的数据集（server.db[i].expires）中任意选择数据淘汰

volatile-lfu: 从已设置过期时间的数据集驱逐使用频率最少的键

allkeys-lru:从数据集（server.db[i].dict）中挑选最近最少使用的数据淘汰

allkeys-lfu: 从所有键中驱逐使用频率最少的键

allkeys-random：从数据集（server.db[i].dict）中任意选择数据淘汰

no-enviction（驱逐）：禁止驱逐数据当内存不足以容纳新写入数据时，新写入操作会报错

需要设置淘汰策略为lru或者lfu

2. 命令实现使用scan命令遍历所有的键值对，针对每个键值对使用OBJECT freq 获取该键值对的信息