While I originally didn’t get the case for GPU accelerated databases, it makes more and more sense given that the bandwidth speeds between GPU and CPU are steadily increasing, making the GPU an increasingly attractive option since the latency for GPU<->CPU syncs is diminishing.
It does make coding on the system a bit more difficult, but we found that the performance gains were worth it.
Also I would add that this system seems, at least for now, geared toward solving a specific set of problems Uber is grappling with around time-series data, whereas OmniSci is trying to tackle general purpose OLAP/analytics problems. Not that solving specific use cases is not great/valid, or that they don't plan to expand the functionality of AresDB over time to encompass broader use cases.
That said, there is interesting academic work around GPU sort that achieves even higher performance than Thrust in many scenarios, and we are looking at the feasibility of incorporating a framework we have found particularly promising.