[eclipselink-users] TemporalType.TIMESTAMP and Oracle DATE columns

[Patric@xxxxxxxxxxx]

Hello everyone,

I am encountering the following situation: (tested using EclipseLink 
2.1.3)

1. Consider an Oracle schema a table contains one column, defined as 
type DATE
2. The corresponding entity maps this column as a java.util.Date, 
annotated with TemporalType.TIMESTAMP
3. Within a transaction create a new instance of this entity, and set 
the field of the column to new Date()
4. Persist it to the persistence context and commit the transaction
5. The (now detached) entity is merged back into the persistence 
context using EntityManager.merge()
6. The transaction is commited again

Surprisingly, EclipseLink issues an UPDATE of this record to the 
database although the entity
has obviously not been changed between the first and the second commit.

After some debugging I realized that the cause of this is an 
inconsistency in the granularity
of the time component between the entity and its backup clone.
The backup clone - which has been read from the database within the 
merge() operation - does not contain milliseconds information,
while the entity itself still contains the original Date object, 
storing milliseconds.

I would expect that in case that eclipselink server session is running 
on the oracle platform it should be able to detect
that we have a DATE column here which is not capable of storing 
millis/nanos and hence should not use these for change detection.

Is this behavior intended?


Thank you and best regards,
Patric