adddelete

Adddelete is a term used in some data synchronization and change-tracking contexts to describe a change set that explicitly contains both additions and deletions. In this model, a change is not represented as a single patch or delta, but as two parallel lists: items to be added and items to be deleted. Each added item generally carries a unique key and a payload, while each deleted item is identified by its key.

Definition and representation

An adddelete batch comprises:

- Additions: a collection of new items with keys and associated data.

- Deletions: a collection of keys corresponding to items to be removed.

Change sets can be serialized as two separate lists, or as a single sequence of tagged records that alternate or group additions and deletions. The separation of adds and deletes helps preserve explicit intent and facilitates auditing and conflict resolution.

Applications and usage

Adddelete is used in distributed systems, order-preserving replication, and event-sourced architectures where maintaining a clear history of what was introduced and what was removed is important. It is particularly useful in key-value stores, content management systems, and synchronization protocols where changes need to be applied deterministically and with straightforward rollback or conflict handling.

Advantages

- Clear semantics for both insertions and removals

- Facilitates auditing, idempotence, and conflict resolution

- Can simplify streaming of changes in replication scenarios

Limitations

- Correct application may require ordering constraints to maintain consistency

- Potential redundancy if same keys are added and deleted in quick succession

- Semantics can vary by implementation, leading to interoperability considerations

See also delta encoding, patch, diff, change data capture, and event sourcing.