includes vs joins vs preload vs eager_load in Rails

📰 Dev.to · Hassan Farooq

Master the differences between includes, joins, preload, and eager_load in Rails to optimize your database queries and improve performance

intermediate Published 22 Jun 2026
Action Steps
  1. Use includes to reduce the number of database queries by preloading associations
  2. Apply joins to combine data from multiple tables into a single query
  3. Configure preload to load associations in a separate query after the primary query
  4. Test eager_load to load associations in the same query as the primary data
Who Needs to Know This

Backend developers and software engineers working with Rails can benefit from understanding these concepts to write more efficient code and improve application performance. This knowledge is essential for optimizing database queries and reducing latency.

Key Insight

💡 Understanding the differences between includes, joins, preload, and eager_load is crucial for optimizing database queries and improving performance in Rails applications

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🚀 Optimize your Rails database queries with includes, joins, preload, and eager_load! 🚀

Key Takeaways

Master the differences between includes, joins, preload, and eager_load in Rails to optimize your database queries and improve performance

Full Article

These four all deal with associations, and they're easy to mix up. The way I keep them straight is to...
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