I believe the limit using the current bitcask backend is (40 bytes + average key size) * (replication factor) / (number of cluster nodes * memory capacity of the smallest node). If that factor grows above 1, you can't store any more.
IIRC correctly a 64-node cluster with 24gb of ram per node will handle a few billion 32-byte keys, replicated to three nodes. For larger keyspaces, the current recommendation is to use innodb, which doesn't need to keep keys in memory.
Given that Riak seems to implement buckets "for free" by essentially making them key prefixes under-the-hood, does the bucket name size need to be considered as part of the key size? e.g., if my bucket name is 32 chars and my keys in that bucket are 32 chars, should I be using 64 bytes for average key size?
This is a question I've gotten conflicting answers to.
IIRC correctly a 64-node cluster with 24gb of ram per node will handle a few billion 32-byte keys, replicated to three nodes. For larger keyspaces, the current recommendation is to use innodb, which doesn't need to keep keys in memory.