JPA: what is the proper pattern for iterating over large result sets?

Question

Let\'s say I have a table with millions of rows. Using JPA, what\'s the proper way to iterate over a query against that table, such that I don\'t have all an in-memo

Answer 1

To expand on @Tomasz Nurkiewicz's answer. You have access to the DataSource which in turn can provide you with a connection

@Resource(name = "myDataSource",
    lookup = "java:comp/DefaultDataSource")
private DataSource myDataSource;

In your code you have

try (Connection connection = myDataSource.getConnection()) {
    // raw jdbc operations
}

This will allow you to bypass JPA for some specific large batch operations like import/export, however you still have access to the entity manager for other JPA operations if you need it.