[GitHub] [iceberg] rdblue commented on pull request #4018: [HiveCatalog] Make Hive's external table behavior match with Iceberg table's gc.enabled behavior.

[GitBox <gi...@apache.org>]

rdblue commented on pull request #4018:
URL: https://github.com/apache/iceberg/pull/4018#issuecomment-1029266880


   I'm -1 for changing this in the Iceberg library. The right way to do this is to customize your catalog.
   
   Iceberg has no concept of an "external" table and although it does define `gc.enabled`, I don't think it is a good idea to conflate the two. The `gc.enabled` property is set when it isn't safe to drop table files. For example, when files are shared across branches in Nessie, it isn't safe to delete files using the metadata of any single branch. Imported tables also set this flag because the files may be "owned" by another table. These are narrow cases and `gc.enabled` is a safety valve.
   
   In normal operation, you never want users accidentally turning on `gc.enabled` because it will prevent old snapshots from getting cleaned up and will effectively keep all versions of the table forever. That's really bad.
   
   If the goal here is to avoid purging table data on delete, then there is another way to do that. `gc.enabled` is not the right mechanism to do it.


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