Azure Functions and Caching

You are free to use the usual approaches that you would use in other .NET applications:

• You can cache it in memory. The easiest way is just to declare a static dictionary and put database values inside (use concurrent dictionary if needed). The cached values will be reused for all subsequent Function executions which run on the same instance. If an instance gets idle for 5 minutes, or if App scales out to an extra instance, you will have to read the database again;

• You can use distributed cache, e.g. Redis, by using its SDK from Function code. Might be a bit nicer, since you keep the stateless nature of Functions, but might cost a bit more. Table Storage is a viable alternative to Redis, but with more limited API.

There's no "caching" feature of Azure Functions themselves, that would be ready to use without any extra code.

You can use Azure Cache service (https://azure.microsoft.com/en-us/services/cache/) to cache your data. Basically, In your Azure Function instead of calling database all the time, call Azure cache and use if it is not expired and if it is expired or not set then call database to get the value and populate the cache with appropriate expiry logic (timeout after fixed time or some other custom logic).

You could use Durable Functions and make the database call via an activity or sub-Orchestration, the return value is essentially cached for you then and will be returned without making the underlying call again each time the function replays.