How can I optimize my database queries in Ruby on Rails?

How can I optimize my database queries in Ruby on Rails?

To optimize your database queries in Ruby on Rails, consider using eager loading to reduce N+1 queries, indexing your database columns, and using the select method to retrieve only the necessary fields.

What is eager loading and how does it help?

Eager loading is a way to load associated records in a single query instead of multiple queries. This reduces the number of database calls and improves performance.

Can you give me an example of using eager loading?

Sure! Instead of using Post.all which may trigger N+1 queries, you can use Post.includes(:comments).all to load posts along with their comments in one query.

What about indexing? How do I know which columns to index?

Index columns that are frequently used in WHERE, ORDER BY, or JOIN clauses. You can analyze your query performance using tools like EXPLAIN to identify slow queries.