Is your feature request related to a problem or challenge?

Hashing union types currently fall through to the unsupported data type error, which means group by, distinct, hash joins, and aggregations all fail on union-typed columns

At work, we interact with a lot of JSON and accessing data with -> returns Union types, since JSON values can be any type. Without hash support, we're forced to use ->> which coerces everything to strings, losing type fidelity and perf

I'm working my way up from arrow, which lays the ground work for this feature

• Support Union data types for row format arrow-rs#8828
• Add support for Union types in RowConverter arrow-rs#8839
• Add comparison support for Union arrays arrow-rs#8838

cc @alamb @paddyhoran @tobixdev