expire key seconds

rename oldkey newkey

renamenx oldkey newkey

move key db_index

exits key

type key

keys pattern

ttl key

randomkey

set key-value
setnx key-value
mset key1-value1...keyN-valueN
msetnx key1-value1...keyN-valueN

incr key
decr key
incrby key integer
decrby key integer

getset key-value

lpush key string
rpush key string

lpop key
rpop key

ltrim key start end
lrem key count value

blpop key1 ...keyN timeout
brpop key1 ...keyN timeout

(if有1个非空)

删除第1个非空并返回
(else若都是空或不存在)

阻塞timeout秒或无穷，
直到其他client的push操作或超时。