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From Tomas Pluskal <>
Subject Using JPA for large object sets
Date Mon, 16 Jan 2012 02:14:07 GMT
Dear OpenJPA community,

I am developing a desktop Java (Swing, J2SE) application that handles large amounts of scientific
data (this one:
The amount of data can go up to tens of gigabytes, so it is not possible to store all the
data as Java objects on the heap.

I have no previous experience with JPA/OpenJPA, so I hope to get some advice from more experienced

I would like to develop an elegant solution to store the Java objects in a database and retrieve
the data on-demand, ideally with some support for caching. 
Searching in the internet I found that OpenJPA combined with Derby might provide this kind
of functionality, but I am not sure if such solution would be efficient.

I played with OpenJPA for a while and I managed to implement a simple hello-world type of
program that creates an instance of an EntityManager and stores an instance of my class by
calling EntityManager.persist(instance)
So far it works. Now I am wondering: is there any easy way how to remove the object from memory,
but keep a reference to it, loading the persisted data on-demand using the reference?

I will appreciate your insights!


Tomas Pluskal
G0 Cell Unit, Okinawa Institute of Science and Technology Graduate University
1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
TEL:  +81-98-966-8684

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