4195. Recovery & Backup: disaster-recovery drill — Recover from failure without violating consistency. — SaaS — Node.js + Express + Sequelize

DBMS Published 30 Sept 2026 Updated 30 Sept 2026 0 Views Verified

Scenario: A SaaS application must handle disaster-recovery drill. Recover from failure without violating consistency. Explain the invariant, SQL strategy, transaction/locking behavior, failure handling, observability and test plan. Use MySQL 8-oriented syntax where applicable.

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Answer & Explanation

4 Answers

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Option 1: Run disaster-recovery drill without defining transaction boundaries, retry behav

Run disaster-recovery drill without defining transaction boundaries, retry behavior, or production validation.

Additional Explanation

Correctness depends on explicit invariants, safe SQL, transaction/concurrency handling and verification.

Verified Correct Answer

Option 2: Use a parameterized, transaction-aware MySQL 8 implementation for disaster-recov

Use a parameterized, transaction-aware MySQL 8 implementation for disaster-recovery drill, validate the invariant, and explicitly test concurrency, retries and recovery.

Additional Explanation

Correctness depends on explicit invariants, safe SQL, transaction/concurrency handling and verification.

Verified

Option 3: Use unparameterized dynamic SQL and rely only on application-side validation for

Use unparameterized dynamic SQL and rely only on application-side validation for disaster-recovery drill.

Additional Explanation

Correctness depends on explicit invariants, safe SQL, transaction/concurrency handling and verification.

Verified

Option 4: Disable database protections and repair inconsistent rows manually after disaste

Disable database protections and repair inconsistent rows manually after disaster-recovery drill runs.

Additional Explanation

Correctness depends on explicit invariants, safe SQL, transaction/concurrency handling and verification.