Hibernate object duplication

Question

For example, I have the following db of two tables: Home and Person. There is one-to-many relationship between these tables. In one home many people live.

Now, let assume the following situation. I load one person from a db as a result I load a home in which this person lives. Then I load another person which lives in the same home. The question is what I am loading: a new home object or the same object which was loaded for the first person? Why?

Andrew Lazarus · Accepted Answer · 2012-12-09 22:01:22Z

1

The same Home object. Hibernate keeps track, by PRIMARY KEY, of which objects it already has on hand, and when the Person constructor comes to fill in the Home, a reference to the already existing object will be used.

On the other hand, you should note that Home maybe getting fetched "lazily", in which case only a proxy (placeholder) for this Home will be a field in both Persons.

answered Dec 9, 2012 at 22:01

Andrew Lazarus

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2 Comments

user14416 Over a year ago

How long hibernate stores this history? What is the scope?

Andrew Lazarus Over a year ago

Suggest you read up on Hibernate Sessions and Transactions. In this case, Session lifetime unless you do some detaching and re-attaching by hand.

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