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Data, state and operational correctness

Make state changes understandable across databases, queues and external services. These guides address transaction boundaries, duplicate delivery, leases and rollback plans.

Identify the durable state

List which system owns the result and which writes must succeed together. A process-local flag is not proof of a committed remote change.

Expect interruption

Plan for a crash between a side effect and its acknowledgement. Use durable identifiers and reconciliation where atomicity is unavailable.

Verify recovery

Test competing workers, expired ownership and repeated delivery. Record when rollback is impossible and compensation is required.

Selected reading

This is an editorial selection, not a certification. Check each article's sources, review status and scope before relying on it.

• Keep transaction boundaries visible

  Document which state changes commit together and what can happen between database transactions and external calls.

• Make duplicate delivery harmless

  Commit a deduplication marker and the intended database effect together, while treating external effects as a separate consistency problem.

• Use expiring leases for distributed jobs

  Protect a reclaimed job from a delayed previous worker with ownership checks and a monotonically increasing fencing token.

• Design rollback before rollout

  Write a recovery decision tree before deployment, distinguishing reversible configuration changes from data migrations that need compensation.

• Measured PostgreSQL SKIP LOCKED claims with four concurrent queue consumers

  Four concurrent transactions each claimed 25 synthetic jobs in PostgreSQL 16.15. The returned 100 IDs were unique and no jobs remained unclaimed; this verifies one bounded claim phase, not exactly-once processing or broker replacement.

• Browser storage: cookies, Web Storage and IndexedDB compared

  Cookies travel with every request and are small by specification; localStorage and sessionStorage are synchronous string stores with a few MiB per origin; IndexedDB is asynchronous, transactional and shares the origin's large quota. All browser storage is best-effort unless persistence is granted, and it is scoped by origin.

• Date and time formats in APIs: ISO 8601 and RFC 3339

  Exchange timestamps as RFC 3339 strings with an explicit offset, dates as YYYY-MM-DD, durations as ISO 8601 durations or plain seconds; never as locale-dependent text or as ambiguous numbers.

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