Early Materialization (ARCH4056)

Key java.orm.early-materialization · Severity warning · Category orm

Filtering or sorting in memory after materializing the query to a list moves work that belongs in the database into the application. Push the predicate into the query.

Incorrect

List<Order> all = orderRepository.findAll();
List<Order> paid = all.stream()
        .filter(o -> o.getStatus() == PAID) // whole table in memory
        .collect(toList());

Correct

List<Order> paid = orderRepository.findByStatus(OrderStatus.PAID);

Fix

Push filtering/ordering/aggregation into the database via WHERE/ORDER BY, not in memory.