BulkInsert schema fetching

[aldiesel]

Is your feature request related to a problem? Please describe.
Extra roundtrip/queries to validate BulkInsert schema.

Describe the solution you'd like
It would be great to cache the columns/metadata when fetching the table schema or allow the user to provide a cached option. I'm not sure if this is reasonable but it would definitely improve query performance.

Describe alternatives you've considered
The current implementation is private

Additional context

[aldiesel]

Hi all, bumping this. Let me know if any other information is needed here