How to Write Fast Code in Ruby on Rails

Part of Shopify’s success with Ruby on Rails is an emphasis on writing fast code. But, how do you really write fast code? Let’s talk about a few ways to start writing faster code in Active Record, Rails, and Ruby.

Shopify logo
Shopify
•
Gannon McGibbon
•10 min read•advanced•
--
•View Original
CachingJSONMerbMonolithMySQLRailsRedisRubySQL

Overview

This article discusses strategies for writing fast code in Ruby on Rails, focusing on performance optimization techniques in Active Record, Rails, and Ruby. It emphasizes the importance of understanding query execution, caching, and efficient coding practices to enhance application performance.

What You'll Learn

1

How to efficiently use Active Record to optimize SQL query performance

2

Why caching is essential for improving application speed

3

When to use background jobs to enhance user experience

4

How to minimize memory allocation in Ruby applications

Prerequisites & Requirements

  • Basic understanding of Ruby on Rails and SQL
  • Familiarity with caching mechanisms and background job processing(optional)

Key Questions Answered

How does Active Record's lazy evaluation affect query performance?
Active Record evaluates queries lazily, meaning that queries are executed only when needed. Understanding when finder methods, calculations, and association methods trigger SQL execution is crucial for optimizing performance and avoiding unnecessary database hits.
What are the best practices for caching in Ruby on Rails?
Caching is vital for improving application speed. Best practices include caching complex view compilations and external API calls, using effective key naming, and managing expiration to ensure data remains relevant without unnecessary database queries.
Why should you avoid querying unindexed columns in SQL?
Querying unindexed columns can lead to full table scans, which are inefficient and can cause timeouts at scale. Indexing the necessary columns is essential for maintaining query efficiency and performance.
How can metaprogramming impact Ruby application performance?
Metaprogramming allows dynamic changes to a program's structure at runtime, but it comes with performance costs. Using traditional method definitions is generally faster than metaprogrammed methods, making it important to use metaprogramming sparingly.

Technologies & Tools

Some links below are affiliate links. We may earn a commission if you make a purchase.

Backend
Active Record
Used as the default Object Relational Mapper (ORM) in Ruby on Rails for database interactions.
Tools
Redis
Commonly used for caching and background job processing.
Tools
Large Hadron Migrator (lhm)
Utilized for online MySQL schema migrations to handle scaling migration problems.

Key Actionable Insights

1
Implement caching for frequently accessed data to reduce load times.
By caching data that doesn't change often, such as API responses or complex view compilations, you can significantly enhance application performance and user experience.
2
Use background jobs for long-running tasks to keep the user interface responsive.
Deferring tasks like data processing or email delivery to background jobs allows your application to remain snappy, improving overall user satisfaction.
3
Regularly evaluate and minimize your project's dependencies.
Reducing unnecessary gem dependencies can lead to faster boot times and lower memory usage, which is crucial as your application scales.

Common Pitfalls

1
Relying too heavily on query cache can lead to inefficiencies.
While query cache can improve performance by avoiding redundant SQL execution, it is not persistent and can be disabled. This can lead to unexpected performance issues if your code runs both inside and outside of a request.

Related Concepts

Caching Strategies
Background Job Processing
Performance Optimization Techniques