I'm late to this conversation but in case anyone is still reading ... Sharding is a really simple and comprehensible way to distribute some load and I favor it

I'm late to this conversation but in case anyone is still reading ... Sharding is a really simple and comprehensible way to distribute some load and I favor it for situations that are generally like this. However, if you want to take a baby step, you can shard a database within the same machine by sharding the storage subsystem. That is, instead of splitting up your database between X machines, you split the database between X SSD arrays within the existing machine. Now each table (or whatever) that you've made a shard has a unique storage throughput and bus path and you aren't competing for iops on one array/disk/whatever. Some workloads can gain a lot from that and it might involve simply plugging in a handful of additional SSDs.