Support collection versions
For some types of collections, particularly things like reference data, it is desirable to keep old versions around if they are updated.
- A collection has a current version number, so that the pair (uuid, version_nr) is be enough as a reference to a specific version of a particular collection.
- Whenever a collection get its
namefields updated, a new version is created (a 'snapshot' of the collection-to-be-changed record is created pointing to the updated, most current version.)
- The user can request a collection via an API call that includes past versions.
- The user can search on collections including past versions.
- Whenever a collection changes owner, uuid, storage classes, replication levels and trashed status, its past versions follow it.
- In order to modify a past version, the user needs to copy it into a new collection.
- A new 'History' tab show the currently viewed collection position on a list of versions.
- On the 'History' tab, versions have the possibility to be copied to an entirely new collection and also to be copied as the current version (revert feature) on the history
- The collection's main pane show an indication if its the current version or an old one.
System wide configurations¶
- Flag to enable version history retention (OFF by default)
- All past versions go on the same collections table (so it's easier to do paging)
- New column
current_version_uuidto hold the current version's UUID.
- New column
version_numberto hold a consecutive integer, starting at 1 for new collections.
- The following fields are synced with their past versions counterparts: replication_*, storage_classes_*, trash_at/delete_at/is_trashed, owner_uuid, uuid (update current_uuid to retain database consistency)
- Old versions with the same name shouldn't conflict with each other or other collections.
Updated by Lucas Di Pentima about 6 years ago
- Collections could have a flag that activates a copy-on-write behavior, maybe with a configurable default value.
- The collection update operation could also have a flag to override the collection’s copy-on-write setting. This would allow FUSE driver to have some control over when to checkpoint modifications.
- Collections also would need a field to point to their ancestor collection, being filled with its own UUID or NULL (the latter would allow an easier database migration) when it’s created from scratch.
- When copy-on-write is active and the collection is updated, before doing so it should be copied and saved as a new collection, and its UUID be used to update the ancestor field of the collection being updated. This way we'll have the UUID as a reference to the most recent version and the PDH as reference to the exact version (like git, commit hashes versus branches).
- We may also need a way to distinguish between current versus old versions, so that they can be filtered out from project listings.
- In the case of the user needing to restore an old version to some project, would the standard “copy to project” action be enough?
- For simplicity’s sake, we could start with a linear history:
- Make old version collections immutable to avoid creating alternate version branches
- Add a descendant_uuid field that’s filled up on creation for easy history forward-navigation. This would also allow to distinguish old versions (descendant_uuid != NULL) supporting the above feature.
- Moving a collection to a new project would also include its ancestors
- When trashing a collection, its ancestors should be trashed as well
- Things to consider:
- Should search optionally include the old versions?
- What should happen with attributes like name (collisions), description, properties, replication_desired?
- Should the future storage_classes_desired attribute be treated the same way as trash_at and owner_uuid?
- On the UI side (maybe this is for a separate story):
- Should a collection view show the entire history or its immediate ancestor/descendant, taking into account the performance implications?
- If the user is viewing an old version, some actions should be visibly disabled (eg: Move to project)