In the case of ES the short answer is; we don't. We have fault tolerance in our replication system to guarantee eventual consistency instead. I would say using

In the case of ES the short answer is; we don't. We have fault tolerance in our replication system to guarantee eventual consistency instead. I would say using ES as a consistent source of data isn't really playing to its strengths so we don't use it that way. The consistency you want is determined at read time: If you need consistency then hit MySQL, but for our use case that almost never happens as eventual consistency is usually instantaneous enough. Our other tool is to decouple lookup (which objects to fetch) and population (what data to return for each object). You can mix and match, e.g. do a lookup against an inconsistent ES but still get consistent objects by populating from MySQL (or vice versa). As others have alluded to it depends entirely on the requirements for the result set.