Question posted in
The official documentation can be found here.

Do I need to hash a Redis key before using *SET?

I’m under the impression that one should hash (i.e. sha3) their Redis key before adding data to it. (It might have even been with regard to memcache.) I don’t remember why I have this impression or where it came from but I can’t find anything to validate (or refute) it. The reasoning was the hash would help with even distribution across a cluster.

When using Redis (in either/both clustered and non-clustered modes) is it best pracatice to hash the key before calling SET? e.g. set(sha3("username:123"), "owlman123")

Tags:

2

Answers


  1. 0

    No, you shouldn’t hash the key. Redis Cluster hashes the key itself for the purpose of choosing the node:

    There are 16384 hash slots in Redis Cluster, and to compute what is the hash slot of a given key, we simply take the CRC16 of the key modulo 16384.

    You can also use hash tags to control which keys share the same slot.

    Login or Signup to reply.
  2. 0

    It might be a good idea if your keys are very long, as recommended in the official documentation:

    A few other rules about keys:

    • Very long keys are not a good idea. For instance a key of 1024 bytes is a bad idea not only memory-wise, but also because the lookup of the key in the dataset may require several costly key-comparisons. Even when the task at hand is to match the existence of a large value, hashing it (for example with SHA1) is a better idea, especially from the perspective of memory and bandwidth.

    source: https://redis.io/docs/data-types/tutorial/#keys

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search