WHAT IS THE N+1 QUERY PROBLEM AND HOW TO SOLVE IT?

Summary from the TLDR Web Dev newsletter

The N+1 query problem is a performance bottleneck where a program makes one initial query and then N additional queries within a loop. The problem happens when fetching related data, resulting in excessive database traffic and slow application performance. The solutions include using a single query with a JOIN or fetching related data in batches using an IN clause, then building the relationship in code.