Redis 查看value大小

线上会经常遇到大key问题，这时候就需要通过–bigkeys来找出最大的key，但是往往和最大的key前缀相同的一类key都会比较大，所以打算一次性获取此类key中比较大的key，官方文档中查看获取value大小的时间成本较高，于是查看有关bigkeys分析这块的redis源码来获取查询命令

代码文件：redis-cli.c
入库函数：findBigKeys 中的主要逻辑

1. 定义了不同数据类型对应的value大小单位

char *typename[] = {"string","list","set","hash","zset","stream","none"};
char *typeunit[] = {"bytes","items","members","fields","members","entries",""};

1. 循环scan key 直到所取的key的数量是10万的倍数
   每取一个key会调用两个函数获取type和value大小

   /* Retreive types and then sizes */
   getKeyTypes(keys, types);
   getKeySizes(keys, types, sizes);

1. getKeySizes中定义了每中类型对应的查询value的命令

char *sizecmds[] = {"STRLEN","LLEN","SCARD","HLEN","ZCARD"};