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Set based thinking

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

Many conceptual differences that you may encounter between using JPA and jOOQ are not technology specific, but a matter of how you think about your database interactions. Neither approach is "the best" one, both approaches are each better suited to certain use-cases. The approaches being discussed here are:

  • Working with entity state transitions (where JPA shines)
  • Working with data set transformations (where jOOQ / SQL shine)

A typical application will have both of the above problems, maybe one type of problem more than the other. It is important to recognise that if you do have both problems, using both types of technology next to each other is a perfectly fine option! Using jOOQ and using JPA aren't mutually exclusive.

Having said so, jOOQ is used most efficiently when following the SQL paradigm of set based thinking. I.e. don't do this:

FOR rec IN (SELECT id FROM book WHERE title LIKE 'A%') LOOP
  UPDATE book
  SET last_update = CURRENT_TIMESTAMP
  WHERE book.id = rec.id;
END LOOP;

But do this, instead:

UPDATE book
SET last_update = CURRENT_TIMESTAMP
WHERE title LIKE 'A%';

The example deliberately didn't use any Java or even JPA code to show the idea that set based thinking isn't strictly related to writing SQL. The first example exposes the N+1 problem via PL/SQL code. It may be perfectly fine to implement entity state transitions on an individual per-row basis in some cases, but in a lot of cases, it's much better to treat your data as data sets and run bulk queries.

Getting a deep understanding of this distinction is out of scope for this reference manual. It takes a lot of practice to do both approaches. But it's important to be reminded of this distinction when you want to switch from JPA to jOOQ. jOOQ embraces the SQL paradigm of set based thinking, and so should you, when you want to use jOOQ most effectively.

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