Reconstitution

Reconstitution answers: how is usable state recovered?

Reconstitution turns persisted material back into current, usable observations of state so that observers, entities, workflows, projections, and processes can continue operating.

Common strategies include:

Load the latest record and produce an observation.
Replay event-sourced committed events and fold them into a current observation.
Load a snapshot plus subsequent events.
Restore CRDT replica state and causal metadata so merge semantics remain valid.
Resume durable execution state, checkpoints, or workflow history.
Activate an actor by identity.
Rebuild a projection as an observation.

The chosen strategy depends on what persistence made durable and what the observer needs in order to interpret new inputs.

In CQRS, reconstitution often happens on the query side through projections, materialized views, caches, indexes, or other read models derived from authoritative write-side persistence.

In database recovery, reconstitution may be hidden inside the storage engine. ARIES-style recovery reconstructs a coherent database state from pages, checkpoints, and write-ahead log records by replaying redo and undo work according to transaction status and log sequence numbers.

Reconstitution and persistence form a useful duality: persistence records selected material as recoverable truth, while reconstitution recovers usable observations from that material. The result can only be as complete as the persisted material and the reconstitution rules allow.