Ruby on Rails Research & Evidence-Based Practice 2

Question 1

Which Rails tool is best suited for benchmarking controller action performance to make evidence-based optimization decisions?

Accepted Answer

ActiveSupport::Benchmarkable

Answer

ActiveSupport::Benchmarkable provides the `benchmark` method to measure and log execution time of code blocks directly in Rails.

Question 2

When evaluating database query performance in a Rails app, which log metric is the primary evidence of N+1 query problems?

Accepted Answer

Repeated identical SQL SELECT statements in logs

Answer

N+1 problems appear as the same SQL SELECT pattern repeated many times in Rails logs, once per associated record.

Question 3

A Rails team wants to validate whether eager loading reduces page load time. Which gem provides automated N+1 detection in test suites?

Accepted Answer

Bullet

Answer

The Bullet gem detects N+1 queries and unused eager loading during test runs, alerting developers to performance issues.

Question 4

Which Rails environment is most appropriate for running reproducible performance experiments with production-like data?

Accepted Answer

staging

Answer

Staging mirrors production configuration, making it the most reliable environment for evidence-based performance experiments.

Question 5

What does the `explain` method on an ActiveRecord relation return, and why is it used in research-driven optimization?

Accepted Answer

The database query execution plan

Answer

`explain` returns the database's execution plan (e.g., EXPLAIN output), showing index usage and scan types for optimization research.

Ruby on Rails Practice Test