Rollback after a database cutover is the restoration of an accepted operating arrangement while accounting for transactions accepted during the transition. Before the target receives new writes, returning traffic can be relatively contained. After new writes, reversal must also preserve or explicitly resolve those transactions.
AWS cutover guidance makes this distinction by identifying the need to transfer new target-side data back during rollback. The point at which the target becomes a writer changes the recovery obligation, even if the routing switch remains easy to reverse.
Define authority before moving traffic
The transition plan should identify the authoritative store for each dataset and operation at every stage. Include jobs, integrations, administrative tools, and clients that can bypass the main application route.
A write freeze or synchronization method needs a clear beginning, end, and reconciliation point. A routing change cannot enforce authority if an overlooked scheduled job continues updating the old database directly.
Go/no-go criteria should name a decision owner and the evidence required before accepting target writes. They should also state when new evidence makes forward recovery preferable to attempted reversal.
A snapshot records a past state
A source snapshot can provide a recoverable baseline. It does not contain transactions created later on the target. Restoring it without a disposition for that later work can restore technical operation while losing accepted business changes.
Take a constructed cutover in which users create orders on the target before a reporting failure is discovered. Returning to the source requires those orders, their identifiers, and any related effects to be reconciled. The reporting failure does not make the orders nonexistent.
External actions deserve attention at the same boundary. A notification or submitted instruction may already have left the database’s transaction scope and cannot be reversed by restoring rows alone.
Forward capture is not a reverse path
Replication configured from source to target establishes a direction and a scope. A reverse path needs compatible mappings, captured history, permissions, and conflict handling, particularly when schemas or business rules differ.
Debezium’s PostgreSQL connector documents possible duplicate events during recovery and failure when a recorded WAL position is unavailable. A rollback design using change capture must account for those limits instead of assuming uninterrupted, exactly-once history.
Rehearsal should include connector restart and an outage long enough to challenge retained history. A low observed lag during normal operation is insufficient evidence for recovery after the relevant failure.
New writes exercise state beyond rows
PostgreSQL 18 logical replication excludes schema changes and sequence state. Replicated identity-column values do not automatically place the subscriber sequence at a safe value for new allocation.
A target can therefore contain matching rows while still needing separate preparation before accepting inserts. The reverse path can face corresponding readiness questions when the old store resumes authority.
Validate schema, generated identifiers, routines, permissions, and required transactions alongside table contents. These PostgreSQL details illustrate a scoped replication boundary; other engines need their own object-coverage evidence.
Rehearse the decision under divergence
A useful exercise switches controlled traffic, accepts representative target writes, introduces a defined failure, and executes the proposed reversal or forward-recovery procedure. Reconcile every transition transaction to an authoritative destination.
Record recovery time, unresolved exceptions, decision deadlines, and responsibilities using the actual scenario. There is no universal rollback window or automatic reverse-replication guarantee.
Acceptance requires more than a working old endpoint. Every transaction accepted during the transition needs a tested disposition, and operators need evidence sufficient to choose and complete the recovery route.