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* Redis中所说的数据结构是针对key-value中的value而言的。
* 主要的结构包括String、哈希表、列表、集合等等
* 在redis中存在16个库,涉及到后期的集群搭建只能使用0号库最为方便
<>查看所有键(支持通配符)
keys * keys S*
<>返回当前数据库中的键总数
dbsize
使用该方式调用的是redis内置的键总数变量,时间复杂度O(1)
<>查看键是否存在
exists
<>删除键
<>键过期
* reds支持设置键过期时间,到期自动删除,单位为秒
* 查看过期时间 pttl的查询可以精确到毫秒级别
<>设置键在毫秒的时间后过期
<>设置在毫秒时间戳之后过期
<>persist命令可以将已经设置过期时间的key,过期时间删除
<>对于字符串String类型的键,重新设置值的时候过期时间会丢失
<>redis中不支持对value内部的结构进行单独的过期时间限制,例如不能对一个list中某一个元素单独设置过期时间。
<>查看键的数据结构类型
<>随机返回一个键
<>键中已经存在某个值,重命名某个键那么其中的值也会被覆盖
* 问题避免
<>Redis键名命名
* 不宜过长,避免浪费内存资源
* 可以使用业务名:对象名:id的方式