######################
发现大keys：
[work@a8-dba-cloud-db00.wh cdrom]$ ./redis_7001/bin/redis-cli -a jJAV0kTokNb8iZvwfqniCxmFZEsbOH5n -c --bigkeys -p 7001 -h 192.168.31.33
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 '"mykey84336"' with 5 bytes
[00.00%] Biggest list found so far '"mylist170898"' with 1 items
[00.00%] Biggest hash found so far '"obj135479"' with 1 fields
[00.00%] Biggest string found so far '"mykey345061"' with 6 bytes
[02.00%] Biggest list found so far '"mylist"' with 410013 items
[25.94%] Biggest hash found so far '"obj"' with 410014 fields
-------- summary -------
Sampled 615176 keys in the keyspace!
Total key length in bytes is 6395083 (avg len 10.40)
Biggest list found '"mylist"' has 410013 items
Biggest hash found '"obj"' has 410014 fields
Biggest string found '"mykey345061"' has 6 bytes
205144 lists with 615156 items (33.35% of keys, avg size 3.00)
205110 hashs with 615123 fields (33.34% of keys, avg size 3.00)
204922 strings with 1173982 bytes (33.31% of keys, avg size 5.73)
0 streams with 0 entries (00.00% of keys, avg size 0.00)
0 sets with 0 members (00.00% of keys, avg size 0.00)
0 zsets with 0 members (00.00% of keys, avg size 0.00)
解决大keys：
- 当Redis版本大于4.0时，可使用UNLINK命令安全地删除大Key，该命令能够以非阻塞的方式，逐步地清理传入的Key；
- 当Redis版本小于4.0时，避免使用阻塞式命令KEYS，而是建议通过SCAN命令执行增量迭代扫描key，然后判断进行删除。
