Solving the N+1 problem

The N+1 problem is not new to Java developers. You might have encountered this problem while using Hibernate, which occurs if you don’t optimize your queries or write entities properly.

Let’s look at what the N+1 problem is.

What is the N+1 problem?

The N+1 problem normally occurs when associations are involved. There are one-to-many relationships between the customer and the order. One customer can have many orders. If you need to find all the customers and their orders, you can do the following:

1. First, find all the users. This find operation returns the list of user objects.
2. Then, find all the orders belonging to each user found in step 1. The userId field acts as the relation between the Order and User objects.

So, here, you fire two queries. If you further optimize the implementation, you can place a join between these two entities (Order and User) and receive all the records in a single query.

If this is so simple...