I have been trying to implement column level access policies on a Big Query external table. I have tried to create a policy tag via GCP console as well as REST API but getting an error "Policy tags are not supported on plain external tables. Use an authorized external table instead". Can anyone confirm is this an expected behavior that external tables are not supported for Policy Tags or is there any way we can implement it?
Error messages also say "Use an authorized external table instead", did they mean use "Authorized Views"?
Worked with Google's support Team and found that (with the help of BigQuery engineering team) Policy Tags are not supported for external BigQuery tables as of now. Authorized View is the current way of implementing column level security in BQ External Tables.
Update: Big Lake Tables is supporting column level policy tagging and row level access control now.