【Redis】【21】查找key

keys *

127.0.0.1:9879> help scan

SCAN cursor [MATCH pattern] [COUNT count]
summary: Incrementally iterate the keys space
since: 2.8.0
group: generic

HashMap

底层类时hashmap 结构
查找时 cursor从0开始到0结束

缺点可能会少扫描一部分
1.扫描到一半的时候，在前半部分新增了
2.扫描的过程中发生了rehash

127.0.0.1:9879> help keys

KEYS pattern
summary: Find all keys matching the given pattern
since: 1.0.0
group: generic