> -----Original Message----- > From: Miłosz Tylenda [mailto:mtyle...@o2.pl] > Sent: Thursday, December 31, 2009 1:35 AM > To: users@openjpa.apache.org > Subject: Re: Can I map between multiple datasources? > > > > I've been assembling an app using OpenJPA 1.2.1 for a few weeks now. > > I've just come to the conclusion that the app is going to require > > reading data from more than one database datasource. One user schema > > has most of the tables, but another user has some other tables. > There > > are some references between those groups of tables. > > > > There's no way to specify multiple datasources in a single > persistence > > unit, but I suppose I could implement multiple persistence units. Is > it > > possible to have an entity from one persistence unit reference an > entity > > from another persistence unit? > > I don't think there is a possibility to have an entity from one > persistence unit reference an entity from another persistence unit. > > It is my understanding that your tables reside in multiple schemas and > you are able to perform joins between tables from different schemas at > the SQL level. If this is the case, you can take advantage of orm.xml > and annotations - they allow you to specify a schema for each table, > for example: > > @Table(name="CUST", schema="RECORDS")
This looks much more promising than trying to get multiple persistence units working together. It all depends on whether I can be allowed to do this in our production database. Here's hoping. Thanks. > Another idea is to check whether your database allows creation of > synonyms/aliases. For example, with Oracle you should be able to > execute DDL like: > > create synonym CUST for OAK.CUST; This is really just a syntactic sugar version of the previous. It won't matter to JPA whether I use a synonym or reference the schema.table directly.
