The shard key

Level 33 of 41

Choose

One user sends two thirds of all new orders. All orders have today's date. Choose a key that keeps three equal shards below their load limit.

Goals

Not tested yet

99 of 100 requests finish faster than this.The share of requests that get a correct answer.How busy the busiest CPU is. Keep room for spikes.What the servers and services cost each month.
Choose a design
Use the user
Use the date
Hash the order ID