redis大key问题

文档

官方文档

官网操作命令指南页面：https://redis.io/docs/latest/commands/?name=get&group=string
Redis cluster specification

说明

redis版本：7.0.0

redis大key问题

安装redis

以单机版redis为例，安装redis参考文档：redis单机安装

什么是大key

大key并不是说key的本身，而是说value
《阿里云Redis开发规范》约定，String类型控制在10kb以内，hash、list、set、zset元素个数不要超过5000
String的value，最大512MB，但是大于10kb就是大key

如何发现大key

连接redis-cli添加--bigkeys参数，可以列出每种类型最大的key，以及每种类型key的个数和平均大小

命令：

shell 复制代码

cd /opt/module/redis/bin
./redis-cli -a 123456 --bigkeys

返回信息：

properties 复制代码

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.

# 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 '"k102211"' with 7 bytes
[00.86%] Biggest list   found so far '"list1"' with 3 items
[18.00%] Biggest set    found so far '"set1"' with 3 members
[45.00%] Biggest string found so far '"k1000000"' with 8 bytes
[57.52%] Biggest zset   found so far '"zset1"' with 5 members
[100.00%] Sampled 1000000 keys so far

-------- summary -------

Sampled 1000003 keys in the keyspace!
Total key length in bytes is 6888910 (avg len 6.89)

Biggest   list found '"list1"' has 3 items
Biggest string found '"k1000000"' has 8 bytes
Biggest    set found '"set1"' has 3 members
Biggest   zset found '"zset1"' has 5 members

1 lists with 3 items (00.00% of keys, avg size 3.00)
0 hashs with 0 fields (00.00% of keys, avg size 0.00)
1000000 strings with 6888896 bytes (100.00% of keys, avg size 6.89)
0 streams with 0 entries (00.00% of keys, avg size 0.00)
1 sets with 3 members (00.00% of keys, avg size 3.00)
1 zsets with 5 members (00.00% of keys, avg size 5.00)

返回信息提示，可以用-i 0.1参数，使程序休眠 0.1 秒每100条SCAN命令（通常无需使用）。

memory usage key命令，返回指定key占用多少子节内存

命令：
shell 复制代码
```
127.0.0.1:6379> memory usage set1
(integer) 64
```

如何删除大key

String类型，使用异步删除，unlink
list、hash、set、zset类型，使用渐进式删除，即先删除里面的元素，再删除key本身

待补充