Exception is not thrown immediately in Hibernate 3. Why??

Question

I am using Hibernate 3.
If I execute "session.update" and the update is not successful (e.g. value too large), the exception is not thrown immediately.
For example,
System.out.println ("pass 1");
session.update(dataBean) ;
System.out.println ("pass 2");
session.getTransaction().commit();
System.out.println ("pass 3");
I find if session.update(dataBean) fails, "pass 1" and "pass 2" are printed but "pass 3" is not printed. That meams Hibernate will not throw exception until I execute "commit". Can I force it to throw immediately (i.e. only "pass 1" will be printed) ?
Thanks in advance.

Answer 1

O/R mappers such as Hibernate and JDO generally defer communications with the database for as long as possible; for an insert or update transaction that will be until commit().
This is for several reasons:
1) general efficiency - a series of update() calls may modify the same attribute of an object multiple times; it's substantially more efficient to update the database just once
2) database efficiency - when a transaction is in progress, even when nothing is occuring in that transaction, more resources are consumed inthe database than when no transaction is active. For example, if a transaction updates a row and then 10 minutes later commits, then during that interval the database has to keep track of 2 different versions of that row and know which connections see which version of the row.
3) connection management - DB connections are expensive resources and once a transaction has started updating the DB, it has to tie up a connection for the duration.
In other words, no matter how long it takes to set up your transaction in Java, a good O/R mapper is not going to begin a database transaction until the last possible moment, which is at commit().
Can I force it to throw immediatelyYou can call commit() any time you want.
It sounds like you want the database to do your input data validation for you. That's wrong. You need to validate input (for size, length, whatever) before you attempt to put it in the database.