What TTL to set for currency exchange cache?

Question

Spring

We have a microservice for currency exchange rate. Our application asks him for the exchange rate, but this takes some time. To reduce the request time and load on the side of our application, there is a cache that stores all these currency exchange rates with TTL in one day. But since the exchange rate changes many times a day and the exchange does not work on weekends, TTL per day does not look optimal. Maybe someone met such a problem and maybe someone has at least some ideas. The application is written in Spring Boot, Hazelcast is used for the cache.

Answer 1

This is more of a question for your business.
IMHO, this information should not be cached at all.
You can try to solve the problem with locks using a reactive approach.