Dear hibernate gurus,
I'm having severe difficulties to handle multiple-columns version checking (optimistic locking) with hibernate version 3.2.
I'm working on a java application using hibernate to access a legacy database used by several legacy systems.
The legacy systems use 2 columns for optimistic locking related checkings, a first one which is the DATE of the change and a second which is the TIME (hh:mm:ss) of the change.
I know how that seems but I can't have 800 legacy tables to change their structure just because I ask for it ... So I have to deal with this 1 second precision version checking :-(
Anyway that's not the subject here ...
So I ended up with the following definition in my mapping file:
Code:
<typedef name="JTVersion" class="xxx.JTVersionType" />
...
<version name="version" type="JTVersion">
<column name="DATE_CHG" />
<column name="TIME_CHG" />
</version>
I obviously defined the JTVersionType as
Code:
public class JTVersionType implements VersionType, AbstractComponentType, Comparator<Object> {
...
The implementation was really simple, easy and straigth forward.
Now, unfortunately, this just CAN'T work :-(
Hibernate just can't handle multiple-columns version checking at the moment And this is why :
Hibernate uses the
version property as an additional column in the where clause of the update statement for optimistic locking purpose.
The problem is that there can only be, no matter what I try,
ONE SINGLE and only ONE version column, never more.Have a look at the class
Quote:
org.hibernate.persister.entity.AbstractEntityPersister
line 118 :
Code:
private final String versionColumnName;
Only ONE single column name is possible ...
This is confirmed everywhere :
Quote:
org.hibernate.persister.entity.AbstractEntityPersister
line 474 - 481 :
Code:
// VERSION
if ( persistentClass.isVersioned() ) {
versionColumnName = ( ( Column ) persistentClass.getVersion().getColumnIterator().next() ).getQuotedName( factory.getDialect() );
}
else {
versionColumnName = null;
}
Look at the code above : it uses "getColumnIterator().next()" . Hence only the first column in my mapping definition can be used by the where clause of the update statement.
And so on ...
Quote:
org.hibernate.sql.Update
line 22 :
Code:
private String versionColumnName;
One single column is possible for version checking, never more, everywhere.
It seems that I am not the first one who has that problem :
http://opensource.atlassian.com/projects/hibernate/browse/HHH-438
Notice that the UserVersionType interface is not helpful at all when it's about multiple-columns version checking.
So what am I missing ?
Is there any hidden mecanism I haven't seen which I could use for implementing multiple-columns version checking ?
Is there any plan to support this feature sooner or later within hibernate ?
Should I work on the required changes to support multiple columns version checking, would you be interested in integrating it into the hibernate sources ?
Hey many thanks in advance for your answers guys :-)
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