Hasty Treat - What is the n+1 problem?

In this Hasty Treat, Scott and Wes talk about a common problem you’ll encounter in your development career — the n+1 problem.

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Show Notes

05:00 - What is the n+1 problem?

• The N+1 problem can happen in any language but is especially prevalent in GraphQL because it’s so easy to query relationships.

09:33 - The solution

• The solution to the n+1 problem is to batch the queries. As you loop over each podcast, keep an array of host IDs to lookup. Once you have looped over the podcasts, make a single query to the database with your large array of podcast host Ids.

11:11 - Should you care?

• Sometimes no: its often fine to do multiple DB Calls
• Facebook DataLoader
• Mercurious
• Many ORMs take care of this for you
  • These then break it down into my appropriate SQL
  • MongoDB Ruby: eager loading
  • Laravel ORM does it
  • Aggregation pipelines
• Prisma N+1: https://www.youtube.com/watch?v=7oMfBGEdwsc&vl=en
• Mongoose Populate
• Apollo Studio

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