3033. Lock queue: Claim up to 20 pending jobs without waiting for jobs locked by another worker. — Multi-language REST API

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

In a lock queue module, solve this as a production problem using Multi-language REST API: Claim up to 20 pending jobs without waiting for jobs locked by another worker. Provide the SQL, explain the logic, show safe application integration, and mention failure/edge cases.

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Answer & Explanation

4 Answers

Verified

Option A

SELECT * FROM table_name;

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.

Verified Correct Answer

Option B

START TRANSACTION; SELECT id FROM jobs WHERE status='pending' ORDER BY id LIMIT 20 FOR UPDATE SKIP LOCKED; UPDATE jobs SET status='processing' WHERE id IN (...); COMMIT;

Additional Explanation

SKIP LOCKED can support worker queues. The actual IDs should be passed safely from the selected rows.

Verified

Option C

UPDATE table_name SET status='active';

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.

Verified

Option D

DELETE FROM table_name;

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.