Xiaoxuan

> available reser Thanks for the explanation!

> @xiaoxmeng This PR is very large, > 1K lines. Would it be possible to break it up into smaller pieces? Can the 3 fixed for pre-existing issues listed in...

> Do you use "UNION" or "UNION ALL" semantics here? It is UNION ALL semantics here. In some structured storage system, we use union iterator to return the unordered stream...

> SpillBatch @oerling Thanks for the review!

> @xiaoxmeng I haven't had a chance to read the changes yet, but I noticed that you are using the term "union" for combining streams. SQL UNION combines data and...

Verified by @zhztheplayer

> Have you considered putting this session property in the PrismConnector? The config value is in free form so any hive storage backend can leverage to optimize the physical data...