Comments on Code Instructions: Read-Only transactions with Spring and Hibernate

Note that when using Spring with Hibernate you gen...

2011-11-07T09:44:00.120-05:00

Note that when using Spring with Hibernate you generally use HibernateTemplate...

And guess what? There's another security at this level:
org.springframework.orm.hibernate3.HibernateTemplate.checkWriteOperationAllowed(HibernateTemplate.java:1175)

This really good article. I have question for auth...

2011-11-02T17:17:58.067-04:00

This really good article. I have question for author. You mention at the end that - "Even during Spring read-only transactions, Hibernate queries still save the state of persistent objects in the session cache".

What happens to these object that are change in cached?
Do they get written to database at any point?
If different session does flush, do these object get persisted at point of time?
If different session is trying to access object which is modified in cache by different read only session. will first session get the value from cache?

I would appreciate if you answer above.

Thanks in advance.

Hi, AFAIK it is different when you set read only t...

2011-06-22T04:10:08.146-04:00

Hi, AFAIK it is different when you set read only transaction and read-only JDBC connection on Oracle. But I have forgotten already the details.

Artem is right. Unfortunately read-only connection...

2010-11-03T12:15:10.359-04:00

Artem is right. Unfortunately read-only connections are not supported by the Oracle JDBC Drivers.
Here's an excerpt from the JDBC Developer’s Guide and Reference
10g Release 2 (10.2):

"Read-only connections are supported by the Oracle server, but not by the Oracle JDBC drivers.

For transactions, the Oracle server supports only the TRANSACTION_READ_COMMITTED and TRANSACTION_SERIALIZABLE transaction isolation levels. The default is TRANSACTION_READ_COMMITTED."

So TRANSACTION_READ_ONLY isolation level cannot be set through the Oracle JDBC driver.

Isn't the session cache also used to prevent h...

2010-08-10T14:48:20.663-04:00

Isn't the session cache also used to prevent having to load the same object twice? That's still useful, even for a read-only transaction.

Yup, helpful. Thanks.

2010-05-02T15:05:23.735-04:00

Yup, helpful. Thanks.

"When using the Oracle JDBC driver, calling c...

2010-03-04T11:25:29.482-05:00

"When using the Oracle JDBC driver, calling connection.setReadOnly(true) translates into the statement "SET TRANSACTION READ ONLY".
It's not true, oracle docs says that they do not support read-only connections (http://www.oracle.com/technology/docs/tech/java/sqlj_jdbc/doc_library/javadoc/oracle.jdbc.driver.oracleconnection.html#setReadOnly%28boolean%29). I also wrote simple test that confirms that. At least I could do SELECT ... FOR UPDATE w/o any exception.

You rock man. Great post. Keep it up.

2010-01-08T01:34:28.270-05:00

You rock man. Great post. Keep it up.

thank you very much!! great helpfull post!!

2009-08-09T20:00:52.870-04:00

thank you very much!! great helpfull post!!

I question the stmt in the last para: If you stil...

2009-07-16T10:44:18.243-04:00

I question the stmt in the last para:

If you still want to prevent Hibernate from saving the object state in the session cache, you have to manually run the HQL queries in read-only mode. It would be a nice improvement to Hibernate to have a read-only mode to the session so that no object state is stored and no flush executed.

The Hibernate Session has a method:

void setReadOnly(Object entity, boolean readOnly)

Set an unmodified persistent object to read only mode, or a read only object to modifiable mode.

This applies to the object, not to the entire session but it does what you want for the object.

Thanks! that was really useful.

2009-05-28T19:53:29.514-04:00

Thanks! that was really useful.