SYSE.34:11 - SoTA-Echoing

For “How can application and data changes proceed without an unexamined all-at-once switch?”, adapt DORA Database change management and the historical 2014 Parallel Change strategy. Versioned migration and compatible intermediate states are useful; a synchronized outage remains a serious alternative when coexistence costs more than it gains.

Reject treating “write both” or “prefer the new non-null field” as complete concurrency reasoning. Sections 5.2–5.3 use the current PostgreSQL 18 trigger, privilege and isolation contracts to construct one bounded alternative. The cost is engine-specific qualification and a single-authority compatibility adapter, not a general bidirectional migration recipe.

Reopen the relying procedure when representation meaning, writer population, engine behavior, trigger/permission conditions, side effects or recovery limits change. The historical strategy remains useful, but its age or a current database manual cannot qualify an untested production arrangement.