Entity tombstone design

[ktuite]

How do we want to track the UUIDs of entities that have been purged?

PR #1349 logs them in array of the details of a purge event. This issue could be closed by deciding this idea is fine.

     action     |      acteeId       |                          details
----------------+--------------------+------------------------------------------------------------------
 entities.purge | (dataset actee id) | {"entityUuids": ["uuid1", "uuid2", "uuid3"], "entitiesDeleted": 3}

Alternatively, maybe we want to pull that data out and put in a more structured table. Then we're not relying on the audit log for functional information or slowing it down.

It could be a table with the following:

• dataset actee id
• entity uuid
• audit event id

Other purged objects

• Forms (the tombstone is the actee row for that form)
• Submissions (no record is kept, submission.purge event just logs count of purged submissions)

The list of purged UUIDs is used to

• prevent reuse of entity uuid
• communicate to Collect via integrity URL which entities have been purged