N Plus One Query (ARCH5050)

Key go.orm.n-plus-one-query · Severity warning · Category orm

Running a separate query per element inside a loop (N+1) is the classic ORM performance killer. Fetch all related data with a single JOIN or preload.

Incorrect

var users []User
db.Find(&users)
for i := range users {
    db.Where("user_id = ?", users[i].ID).Find(&users[i].Orders)
}

Correct

var users []User
db.Preload("Orders").Find(&users)

Fix

Fetch related data in a single query with Preload or a JOIN instead of querying per element in a loop.