A product owner comes to you and says that both reading and writing need to be very fast. How would you help him?

To ensure very fast operation and reading and writing, several approaches should be considered:

• Caching: Use cache (e.g., Redis or Memcached) to speed up data reading, especially if data is frequently requested and rarely changed.
• Choosing the right database: For example, NoSQL databases (Cassandra, MongoDB) scale well and provide high speed of writing and reading.
• Sharding and replication: Dividing data into parts (shards) and replication to distribute the load.
• Asynchronous processing: For writing, a message queue can be used to avoid blocking read operations.
• Index optimization: Proper indexing will speed up queries.

It is important to clarify which data and operations are critical for speed to select the optimal solution. Often, there is a trade-off between write and read speed, as optimizing for one can slow down the other.