Redis Cache is a well know caching technology and you can run it in Azure as a fully managed service. A common requirement (the most basic one) is doing a workflow like:
1. When an application needs to retrieve data, it will first search to see if it exists in Azure Cache for Redis.
2. If the data is found in Azure Cache for Redis (cache hit) use it
3. If the data is not found in Azure Cache for Redis (cache miss), then the application will need to retrieve the data from Azure SQL (or whatever cloud db back end you use)
4. For cache miss scenarios, the requesting application should add the data retrieved from the Azure Database to Azure Cache for Redis.