Redis Cross Slot error

Question

I am trying to insert multiple key/values at once on Redis (some values are sets, some are hashes) and I get this error: ERR CROSSSLOT Keys in request don't hash to the same slot.

I'm not doing this from redis-cli but from some Go code that needs to write multiple key/values to a redis cluster. I see other places in the code where multiple key values are done this way and I don't understand why mine don't work. What are the hash requirements to not have this error?

Thanks

Answer 1

In a cluster topology, the keyspace is divided into hash slots. Different nodes will hold a subset of hash slots.

Multiple keys operations, transactions, or Lua scripts involving multiple keys are allowed only if all the keys involved are in hash slots belonging to the same node.

Redis Cluster implements all the single key commands available in the non-distributed version of Redis. Commands performing complex multi-key operations like Set type unions or intersections are implemented as well as long as the keys all belong to the same node.

You can force the keys to belong to the same node by using Hash Tags

Answer 2

ERR CROSSSLOT Keys in request don't hash to the same slot

As the error message suggests, only if all of the keys belong to same slot will the operation succeed. Otherwise, you will see this failure message. This error would be seen even though both/all slots belongs to the same node. The check is very strict and, as per the code, all keys should hash to same slot.