N+1 query problem causes excessive database calls

This is the silent killer. Your app works fine with 10 users, then dies with 100... Post.includes(:user).each { |post| puts post.user.name } Lightning fast - loads all users at once

Use query inside the loop: Most of the time we use to add queries inside the loop... suppose there are 200 records are there and we are calling query for each of them, then we are requesting 200 resources from MySQL. This type of code will slow the execution of the code and lots of MySQL resources will be miss utilized.

N+1 queries are one of the most common database problems that can easily go unseen (until the query overwhelms your database and in some cases takes down your application)... But for most, this problem can be hard to detect at first, as your website could be performing fine. But as the number of parent objects grows, the number of queries increases too…until your database collapses.

Complex queries sometimes generate unexpected SQL -- multiple queries instead of JOINs...every time Prisma's abstraction hides the SQL, it's also hiding a potential performance issue. And every time I reach for $queryRaw to write manual SQL, I'm stepping outside the safety net that makes Prisma valuable in the first place.

The N+1 query problem happens when a query fetches a list of items, and then runs additional queries for each item to fetch related data, leading to multiple database hits. Root cause: Fetching related data in loops instead of using aggregation or $lookup

Relational mapping breaks down – N+1 queries everywhere unless you hand-optimize. ... It doesn't have any concept of a JOIN, or of the actual relationships between your types (graphql has no concept that me == me.parent.child). You end up writing data loaders for every type so that loops in your schema can be resolved efficiently.

The classic mistake is the N plus1 query problem. Fetching all list items then making a separate database call for each items related data. If you're loading, for example, 20 blog posts and fetching the author for each one in individually, that's 21 queries when it should be two.