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Solving the N+1 Problem in GraphQL
The N+1 problem occurs when we use data returned from the database to fuel a list of further queries to the database.
Meaning, if you receive a list of results from a query, then for each result, you will make another query to the database.
In this case, the N stands for the number of results returned from the database, and 1 stands for the initial query that was made.
To clarify: the problem is that for each of the N results returned, we will have to make another query, so there will be N requests made to the database, plus the 1, which was the initial request.
This can easily become a performance bottleneck.
Example of an N+1 Situation
You want to query the grades for all the students who go to a school. The N+1 problem would occur if you first queried all the students who go to that school, and then made a loop that would query the grades for each student that was returned, one at a time.
Here’s some example pseudocode:
const students = `SELECT * FROM students`students.forEach(student =>
`SELECT * FROM grades WHERE student_id = ${student.student_id}`)
