This isn't an accurate premise. Modern OLAP databases make dealing with billions to trillions of rows manageable, including on a single server. Exporting "select * from table" from an OLTP such as Postgres or MySQL into an OLAP is trivial and quite fast, and if 100M rows/sec on commodity servers isn't fast enough, there's always performance tuning [1].
This isn't an accurate premise. Modern OLAP databases make dealing with billions to trillions of rows manageable, including on a single server. Exporting "select * from table" from an OLTP such as Postgres or MySQL into an OLAP is trivial and quite fast, and if 100M rows/sec on commodity servers isn't fast enough, there's always performance tuning [1].
[1] https://altinity.com/blog/loading-100b-rows-in-minutes-in-al...