Collection version history¶

(draft)

Background: desired API features (#13494, #13561) epic ticket is #13109

• Get current + previous versions of a collection with a single API call
• Search all current + previous versions of collections with a single API call
• Stable small numeric "version number" for each version of a given collection

Implementation

• Store all versions in the collection table (much easier to do paging)
• New database column "current_version_uuid" for latest version this the same as "uuid"
• New database column indicates user-friendly version number (starting at 1) -- can be assigned safely after locking "current" row for update
• Assign version number to the current version -- this way {uuid,version} can be used as a permanent reference to a specific version
• Flag "include_past_versions" for "list" API to include old versions (otherwise, filter on current_version_uuid=uuid -- might need to adjust indexes to maintain performance)
• Flag in site configuration to enable preserving old versions in database
• Update owner_uuid of all old versions (in a transaction) when it changes in the current version
• A permission link to the current version implies permission to its entire history
• Prohibit permission links to old versions (should be handled by check "can only make links to things that are visible to you", which should not include old versions)
• Old versions may not be modified except for certain fields which must be synchronized with "current" version changes (owner_uuid, trash_at, delete_at). Updating owner_uuid, trash_at, delete_at does not update modified_at so modified_at shows when the version was created
• Old versions with duplicate "name" does not conflict with (owner_uuid, name) uniqueness constraint
• The following changes introduce a new version: manifest_text, description, properties.

Questions:

• Should any other field changes introduce a new version, such as changing "name"
• Are desired_replication_count and desired_storage_class separate for each version? Feature to automatically put old versions into a certain storage class?