Tim - Take a look at Large Result Sets[1].
[1] http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_dbsetup_lrs Thanks, Rick On Mon, May 30, 2011 at 7:47 AM, tfriess <[email protected]> wrote: > Hello, > I'm looking for something like a database cursor in OpenJPA and was not > able > to find something similar. (I used Google and also searched this mailing > list/ forum.) > I have to use OpenJPA 1.2.2. > > Using OpenJPAs Query class I can only get a complete list of entities from > the database at once (using the "getResultList()" method). If there are a > lots of entities persisted in the table this (a) could need a lots of time > and (b) loads all the entities into my memory. > What I'm looking for is something like an iterator/ cursor to the results > of > my query where I can get an entity one by one with some kind of > "getNext()"-method which I then can process before I fetch the next entity > from my result. I want to avoid holding all the result entities at once in > a > List in my memory. > > I figured out that I'm able to get a reference to the java.sql.Connection > class via the OpenJPAPersistence. > With this instance I'm able to manually send a query to the database using > the JDBC mechanisms and get a java.sql.ResultSet as result. With this > ResultSet I can exactly do what I want - iterate over the results of my > query. > But the problem here is (a) I'm using OpenJPA internals and not only the > JPA > API and (b) I was not able to figure out how to automatically map a > ResultSet to my real entity class. > > Is there a good solution for my problem? > > Thank you very much! > > Kind regards, > Tim > -- *Rick Curtis*
