Spring - Transaction Readonly

java spring transactions readonly
AAK picture AAK · Apr 1, 2010 · Viewed 24k times · Source

Just wanted your expert opinions on declarative transaction management for Spring. Here is my setup:

  1. DAO layer is plain old JDBC using Spring JdbcTemplate (No Hibernate etc)
  2. Service layer is POJO with declarative transactions as follows - save*, readonly = false, rollback for Throwable

Things work fine with above setup. However when I say get*, readonly = true, I see errors in my log file saying Database connection cannot be marked as readonly. This happens for all get* methods in service layer.

Now my questions are:

A. Do I have to set get* as readonly? All my get* methods are pure read DB operations. I do not wish to run them in any transaction context. How serious is the above error?

B. When I remove the get* configuration, I do not see the errors. Morever, all my simple get* operations are performed without transactions. Is this the way to go?

C. Why would anyone want to have transactional methods where readonly = true? Is there any practical significance of this configuration?

Thank you! As always, your responses are much appreciated!

Answer

Bozho picture Bozho · Apr 1, 2010

This post tells that the behaviour or the readOnly flag is persistence-mechanism-dependent.

C. Yes, when using hibernate, it gives performance benefits by setting the flush mode to FLUSH_NEVER (as described in the linked post)

B. Yes, JDBC calls do not require a transaction (hibernate requires one), so removing the @Transactional configuration trims all transaction management.

A. I'd assume spring is calling connection.setReadOnly(true) but your JDBC driver doesn't support this

The bottom-line is : don't use readonly transactions with plain JDBC.

And another thing - transactions are supposed to span multiple queries. Don't make your transactions too fine-grained. Make them a unit of work.

Related questions

Where does the @Transactional annotation belong?

Should you place the @Transactional in the DAO classes and/or their methods or is it better to annotate the Service classes which are calling using the DAO objects? Or does it make sense to annotate both "layers"?

Read More
Transaction marked as rollback only: How do I find the cause

I am having issues with committing a transaction within my @Transactional method: methodA() { methodB() } @Transactional methodB() { ... em.persist(); ... em.flush(); log("OK"); } When I call methodB() from methodA(), the method passes successfuly and I can see "OK" in my logs. …

Read More
UnexpectedRollbackException: Transaction rolled back because it has been marked as rollback-only

I have this scenario: fetch (read and delete) a record from IncomingMessage table read record content insert something to some tables if an error (any exception) occurred in steps 1-3, insert an error-record to OutgoingMessage table otherwise, insert an success-record …

Read More