5575. Concurrency & Locks: DDL blocking diagnosis — Recover from failure without violating consistency. — inventory — PHP PDO

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

Scenario: A inventory application must handle DDL blocking diagnosis. 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

Verified

Option 1: Run DDL blocking diagnosis without defining transaction boundaries, retry behavi

Run DDL blocking diagnosis 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 DDL blocking d

Use a parameterized, transaction-aware MySQL 8 implementation for DDL blocking diagnosis, 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 DDL blocking diagnosis.

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 DDL blo

Disable database protections and repair inconsistent rows manually after DDL blocking diagnosis runs.

Additional Explanation

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