Presentation from JEEConf conference (Kiev, May 2012) about issues in Hibernate usage and tricks to avoid them.

1. Why do I hate Hibernate?
Mikalai Alimenkou
http://xpinjection.com
19.05.2012

3. CRUD
*R – read by ID

4. Why Hibernate is so popular?
1. EJB 2 sucks!
+
2. New “standard”

5. WTF #1. Nobody understand how
equals and hashCode must look like

6. Comparison context is
very important
Hard to select real
“unique business key”
Performance issues
with collections
Auto-generated
fields in Set

7. WTF #2. Mutable objects are evil

8. Default constructor
must present
Fields can’t
be final
Inconsistent object
state is possible
Or… reflection
magic happens

9. POJO bullshit
game

10. WTF #3. DTO is evil pattern
with Hibernate

11. Lots of code DTO maintenance
duplications is nightmare
Many solutions:
- transformers
- beanutils
- reflection
- libraries
Crazy DTO “don’t
forget” checklist

12. WTF #4. Lazy loading

13. Nightmare for Everything is stupidly
newcomers slow without it
Almost nobody
understand how
it works
Persistent
collections are
not serializable

14. WTF #5. Criteria API or HQL?
=

15. WTF?!?
No need to know
SQL???
Bullshit!!!

16. Different features set in
HQL and Criteria API
Hand made query
builders in HQL
No check for
NULL in HQL
Criteria API only
for READ

17. WTF #6. To update single field
you should read full entity

18. Children and large
Not everybody
fields are loaded
understand how
‘lazy loading’
works
HQL update is not
object-oriented
At least 2 SQL
queries for
simple update

19. WTF #7. Temporary table usage
on update or delete

20. WTF #8. Composite key requires
separate class

21. WTF #9. Entity state can be managed
only from one side in parent-child
relationship

22. WTF #10. Flush on commit is
too unpredictable

23. Entity changes are
persisted
Collections
operations are ‘live’
Constraints are
checked on commit
No control for SQL
queries order

24. WTF #11. Dirty entity after
transaction rollback can’t be reused

25. WTF #12. Documentation is
simple but primitive

26. Only basic samples
For complex are covered
things you need
books
Bug reports are
ignored
Debug hell to
understand how
things work

27. WTF #13. Hibernate makes
developers stupid
Are you
joking???

28. People don’t learn
JDBC and SQL
Nobody count
SQL queries and
care about their
structure
Developers
don’t tune JDBC
properties

29. When we really need to use ORM?

30. Is CQRS more actual now?

31. Useful books

32. @xpinjection
http://xpinjection.com
mikalai.alimenkou@xpinjection.com