# High Performance PostgreSQL for Rails: Explanation regarding the use of includes with a limit (Page 124)

**URL:** <https://forum.devtalk.com/t/high-performance-postgresql-for-rails-explanation-regarding-the-use-of-includes-with-a-limit-page-124/161023>\
**Category:** PragProg Customers\
**Tags:** book-high-performance-postgresql-for-rails, suggestion\
**Created:** [5 July 2024 12:43 UTC](https://forum.devtalk.com/t/high-performance-postgresql-for-rails-explanation-regarding-the-use-of-includes-with-a-limit-page-124/161023 "2024-07-05T12:43:30Z")\
**Posts on this page:** 1\
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**Author:** ![andatki](https://forum.devtalk.com/user_avatar/forum.devtalk.com/andatki/32/5332_2.png) [@andatki](https://forum.devtalk.com/u/andatki)\
**Post date:** [12 July 2025 03:26 UTC](https://forum.devtalk.com/t/high-performance-postgresql-for-rails-explanation-regarding-the-use-of-includes-with-a-limit-page-124/161023/2 "2025-07-12T03:26:22Z")

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Thank you @viktorianer. Your description makes sense. If we revise the book in the future, I’ll pay extra attention to this section, as eager loading is of course a very common pattern.

In my experience, I’ve seen poor performance from big lists of values in an IN clause on big tables. I wrote up some thoughts about this in a blog post here: [Big Problems From Big IN lists with Ruby on Rails and PostgreSQL | Software Engineer, Author, High Performance PostgreSQL for Rails](https://andyatkinson.com/big-problems-big-in-clauses-postgresql-ruby-on-rails)

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