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I'm not that familiar with the requirements of a big OLAP setup but can you explain why they can't be met by creating a logical replica using something like pg_logical?

I understand that the shape of the schema has to be somewhat different for analytics (though I think that point is overstated and many use cases could probably get accomplished with the same table layout but just different index placements)

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Because transactional workloads (many small reads and writes that require consistency) look different from analytical workloads (giant reads with a small number of columns with looser consistency guarantees).

OLAP databases typically use a column store which is amazing for reading a subset of columns because of much better compression and use of vectorized execution as opposed to Postgres’ tuple-at-a-time execution. The tradeoff is it’s expensive to update a column store since you have to rewrite a chunk of the column at least.

Postgres is moving towards better OLAP. AlloyDB is a recent commercial DB that swaps out the Postgres storage engine to better support OLAP.

That said, you can coerce Postgres into doing a reasonable job at OLAP for a surprising amount of data.

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