> Once the databases are selected, the next challenge is ensuring reliable, ongoing data replication from PostgreSQL to ClickHouse. While it’s possible to handle this at the application layer by writing data directly into ClickHouse, replicating data at the database level tends to be simpler and more reliable.<p>I'm curious if you have data that backs this up, or if it's more of a "gut feeling" sort of thing. At first blush, I agree with you, but at the same time, by doing it at the application level, it opens up so many more possibilities, such as writing "pre-coalesced" data to the data warehouse or pre-enriching the data that goes into the data warehouse.