3628. Performance: Find queries that may benefit from an index on customer_id and status. — Concurrency

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

In a performance module, solve this as a production problem using Concurrency: Find queries that may benefit from an index on customer_id and status. 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

Option B

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 C

DELETE FROM table_name;

Additional Explanation

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

Verified Correct Answer

Option D

EXPLAIN SELECT id,total_amount FROM orders WHERE customer_id=:customer_id AND status='completed' ORDER BY order_date DESC LIMIT 50;

Additional Explanation

EXPLAIN is used to validate the access path; index design should follow actual workload and execution plans.