Another replication feature in RavenDB is the ability to replicate only specific collections to a sibling, and even the ability to transform the outgoing data as it goes out. Here is an example of how this looks in the UI, which will probably do it much better justice than a thousand words from me.
There are several reasons why you'll want to use this feature. In terms of deployment, it gives you an easy way to replicate parts of a database's data to a number of other databases, without requiring you to send the full details. A typical
example would be a product catalog that is shared among multiple tenants, but where each tenant can modify the products or add new ones. Another example would be to have the production database replicate backward to the staging database, with certain fields that are masked so the development / QA team can work with a realistic dataset. An important consideration with filtered replication is that because the data is filtered, a destination that is using filtered replication isn't a viable fallback target, and it will not be considered as such by the client. If you want failover, you need...(Read whole news on source site)