Hi all, I would like to share a short update on the Arrow adapter work under [CALCITE-6304][1].
[CALCITE-6304][1] was created as an umbrella issue to improve the Arrow adapter. With the recent focused issues and PRs, the main functional gaps in the Arrow adapter have now largely been addressed. The Arrow adapter now has a more complete baseline for basic SQL usage: schema inference, table scans, projections, filters, null handling, and a broader set of Arrow data types are covered by result-level tests. I would describe the adapter as having reached a basic MVP state for common SQL queries. There are still follow-up areas, especially around more complex nested types and execution-path cleanup, but the adapter is now in a much more usable state than when [CALCITE-6304][1] was opened. I think this may also be useful as a reference for other adapters. Many adapters need to go through a similar path: map source-specific types into Calcite row types, support common SQL projection and filter behavior, handle null values correctly, and verify result correctness from SQL-level tests rather than only checking plans or internal helper methods. Different adapters have different storage models and execution constraints, so the implementation details will differ. But the Arrow work provides one example of how an adapter can reach a basic SQL MVP through focused issues and tests. Thanks, Cancai [1]: https://issues.apache.org/jira/browse/CALCITE-6304
