3979. Performance: Find duplicate expensive queries in an application log table. — Architecture

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

In a performance module, solve this as a production problem using Architecture: Find duplicate expensive queries in an application log table. 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 Correct Answer

Option C

SELECT query_hash,COUNT(*) executions,AVG(duration_ms) avg_ms,MAX(duration_ms) max_ms FROM query_log GROUP BY query_hash ORDER BY avg_ms DESC LIMIT 20;

Additional Explanation

Application-level query logs can identify repeated slow patterns before database tuning.

Verified

Option D

DELETE FROM table_name;

Additional Explanation

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