1.
Hibernate performance
tuning
Mikalai Alimenkou/Igor Dmitriev
http://xpinjection.com
@xpinjection

2.
Disclaimer
This is only my
personal experience

3.
You could follow code samples
https://github.com/xpinjection/hibernate-performance

4.
What Hibernate really does?

5.
Full execution chain

6.
How to measure
• Hibernate statistics with
• Benchmarks with JMH:
– http://openjdk.java.net/projects/code-tools/jmh/

7.
How to understand and trace
• Datasource proxy:
– https://github.com/ttddyy/datasource-proxy
– https://github.com/p6spy/p6spy
• Queries counting interceptor:
– https://github.com/vladmihalcea/db-util
• Log and format SQL statements

8.
Demo database schema

9.
JDBC tuning
• Use good implementation of connection pool
• Batching, fetching
• Switch to native queries where performance is
critical
• Do direct JDBC stuff with Session doWork

10.
N + 1, lazy loading issues
• Eager load
• Entity graphs
• Fetch modes
• Fetch profiles
• Query batching

11.
Operations batching
• Flush Session state to avoid memory issues
• Use JDBC batching options
in order to mix statements for different tables
• Deletes are batched only for the same table

12.
Second level cache

13.
Cache providers and strategies

14.
Query cache

15.
Mark lightweight requests
• Read-only flag for transactions
• Choose appropriate transaction isolation level
• Annotate entity as immutable if it is not
updated anywhere
• Use StatelessSession for some operations

16.
Don’t use entities everywhere
• ResultTransformer and Transformers
• Fields map instead of object
• @SqlResultSetMapping
• Direct mapping on DTO

17.
Don’t update all columns
• Dynamic insert, update
• Update only changed columns
• Be careful with number of PreparedStatement

18.
Slow ID generation
• Id generator mapping
• Don’t use GenerationType.AUTO, use
GenerationType.SEQUENCE instead
• Try to generate ID/PK in the
code, not delegate to Hibernate

19.
Other advices
• Use native queries if really helpful:
– “ORDER BY NULL” or “DELETE with JOIN” in
MySQL
– Effective data removal
• Don’t use lists, arrays and ordering in
Hibernate

20.
Start thinking in CQRS way

21.
When we really need to use ORM?

22.
Resources
• https://vladmihalcea.com/presentations/
• https://vladmihalcea.com/tutorials/hibernate/
• http://jeeconf.com/archive/jeeconf-
2012/materials/hibernate-performance/
• https://docs.jboss.org/hibernate/orm/5.0/manual/en-
US/html_single/#performance
• http://jeeconf.com/program/hibernate-how-the-magic-
is-really-done/
• http://jeeconf.com/program/hibernate-performance-
tuning/

23.
Books to read

24.
@xpinjection
http://xpinjection.com
mikalai.alimenkou@xpinjection.com
ihor.dmitriiev@gmail.com