问题
When using the redis expire commands like SETEXP & TTL, there are scenarios in which there is no need for the key to hold a value at all, because the time to live acts as such.
However, redis requires any key to have a value.
What would be the most reasonable value to use - if you don't ever want to read it?
回答1:
Who said that you should actually store anything in redis key?
Empty string "" is a perfectly valid value for a redis key, and it's a shortest possible one:
> SET foo ""
OK
> GET foo
""
> BITCOUNT foo
(integer) 0
回答2:
I would store one byte of data that could also be broadly interpreted as "truthy", such as the ASCII character 1.
回答3:
Do you serialize everything coming to and from redis, yourself? If so, you may consider using a sentinel value (like a NONE constant, etc.) which is set to something like 'None'.
回答4:
I would avoid using "". How about simple 0 ?
127.0.0.1:6379> set akey 0
OK
127.0.0.1:6379> memory usage akey
(integer) 48
127.0.0.1:6379> set akey ""
OK
127.0.0.1:6379> memory usage akey
(integer) 50
127.0.0.1:6379>
来源：https://stackoverflow.com/questions/25557250/redis-store-key-without-a-value