ETL to bring all your data into Databricks/Snowflake is a lot of effort. Much better if your OLTP data already exists in Databricks and you directly access it from your OLAP layer.
The problem isn't in the CDC / replication tools in the market.
The problem is that columnar stores (especially Iceberg) are not designed for the write /upserts patterns of OLTP systems.
They just can't keep up...
This is a big problem we're hoping to solve at Mooncake [0]. Turn Iceberg into an operational columnstore. So that it can be keep up (<s freshness) with your Postgres.
And for second latency replication, it is more involving, you actually need to build layer on top of iceberg to track pk/ apply deletion.