Let’s say you’ve set up a sharded cluster with data in two zones like in this example:
And you have an application that also runs in two separate regions (one in us and one in Europe). How does the reads and writes from the application running in the European data center get routed to the European shard, and vice versa? Do the two application use different connection strings, so that the routing is handled at the DNS level? Or do both applications connect using the same connection string? If so, won’t that mean that one of the application instances will have to do a cross-region connection, even if subsequent connections are to the closest shard?