Collection version history » History » Revision 15
Revision 14 (Peter Amstutz, 09/06/2018 03:02 PM) → Revision 15/17 (Tom Clegg, 09/06/2018 03:21 PM)
h1. 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
h2. Design
* 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 only implies permission to the most recent version (not the 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 (portable_data_hash), description, properties, name,
* The following changes do not introduce a new version, and a copied to all past version records: replication_*, storage_classes_*, trash_at/delete_at/is_trashed, owner_uuid, uuid (update current_uuid to retain database consistency)
* If the existing version is less than N (site-configurable) minutes old, and has not been explicitly flagged via new API ("commit"?), it is not retained in the version history.
** (PA proposal) add a field "checkpoint_at", which means this version will be checkpointed if an update occurs *after* @checkpoint_at@. Update operations can set @{checkpoint_at: 1970-01-01}@ or use @?checkpoint_after=0@ to ensure a version will be checkpointed. When updating a collection, the @checkpoint_at@ field is reset to @modified_at@ + value of the parameter @checkpoint_after@ provided by the client, or the system default.
** (TC proposal) add a boolean field "preserve_version", which defaults to false on create/update. During an update, save a snapshot in the version history if @preserve_version || (current_timestamp - modified_at > config.version_batch_timeout)@.