redis key-value what the limitation of key?

Question

set "as";b 1 is error 
key:  "as";b
value:   1

what is the naming rule of key?

Redis uses SDS to implement string. Book says SDS can contain any construction of string

Answer 1

A Redis key name can be any string as long as it is under 512MB. Other than that, there are no rules.

Answer 2

Anything goes... up to 512MB

http://redis.io/topics/data-types-intro#redis-keys

other discussion on Redis key naming conventions

Redis key naming conventions?