Once you've decided to distribute data, how should the data be distributed?
Firstly, data needs to be distributed using a partitioning key in the data. The partitioning key can be the primary key or any other unique key. Once you've identified the partitioning key, we need to decide how to assign a key to a given shard.
One way to do this would be to take a key and apply a hash function. Based on the hash bucket and the number of shards to map keys into, the key would be assigned to a shard. There's a bit of nuance here in the sense that an assignment scheme based on a modulo by the number of nodes currently in the cluster will result in a lot of data movement when nodes join or leave the cluster (since all of ...
