Thanks Milosz. You are right. Annotating a class with @Replicated enables Slice to store its instances in multiple databases. This is useful for quasi-static master data such as Country/Currency Code which all other entities may refer. Earlier because of 'collocation constraint', Slice was storing the entire closure of a graph in the same slice -- but with @Replicated and ReplicationStrategy interface -- this restriction has been removed. Few preliminary test cases have been committed to demonstrate its usage. The aggregate queries are also aware of this replicated instances and returns the correct aggregate values.
Miłosz Tylenda wrote: > > Thiago, > > A few weeks ago there was a commit of @Replicated annotation. It might be > what you want. It requires a nightly build of OpenJPA though. Have a look > at > > http://openjpa.apache.org/builds/latest/docs/javadoc/org/apache/openjpa/persistence/Replicated.html > > Regards, > Milosz > > >> I'm sorry...i told you without make the test! It's true, the >> GeneratedValue >> works correctly in "Slices", this is Great! >> >> I have one more question but it's specifically about Slices: >> >> I have a class that makes the Distribution Rules, and the method "public >> String distribute(Object object, List slices, Object context)" >> always returns a String of one Slice! But if i want to persist a object >> in >> all databases or two, what can i do? >> >> Thanks! >> >> >> >> Michael Dick wrote: >> > >> > Sorry about that, I didn't notice the part about slice. >> > >> > As I understand it slice uses the "master" slice to get the next value >> for >> > an autogenerated field. By default the master slice is the first slice >> > listed. The wording in the manual is a little confusing though : >> > >> > >> > >> >> 4.3. openjpa.slice.Master >> >> This plug-in property can be used to identify the name of the master >> >> slice. >> >> Master slice is used when a primary key is to be generated from a >> >> database >> >> sequence. >> >> >> >> By default the master slice is the first slice in the list of >> configured >> >> slice names. >> >> Warning >> >> Currently, there is no provision to use sequence from multiple >> database >> >> slices. >> >> >> > >> > I think the warning refers to >> > @GeneratedValue(strategy=GenerationType.SEQUENCE) not generated values >> in >> > general. >> > >> > I've run some fairly simple unit tests and it looks like the generated >> > values are working. Have you run into errors when using Slice and >> > GeneratedValues? >> > >> > -mike >> > >> > On Tue, Oct 7, 2008 at 9:47 AM, thiago ananias >> > wrote: >> > >> >> >> >> >> >> I understand you! but... >> >> >> >> I'm using "Slice"(A Distributed Database plugin for OpenJPA) and all >> >> database will have his own table "GeneratedValue" and i need a unique >> >> identifier for all databases at the same time! >> >> >> >> Thanks! >> >> >> >> >> >> Michael Dick wrote: >> >> > >> >> > Hi Thiago, >> >> > >> >> > The class you included will work with all databases. Id will be >> mapped >> >> to >> >> > an >> >> > INTEGER column, nome will be mapped to a VARCHAR column, and >> dtInsert >> >> will >> >> > be DATE or TIMESTAMP. The actual mappings are determined by OpenJPAs >> >> > DBDictionary classes - there's one for each database you listed. The >> >> given >> >> > example should work fine with any RDB we support. >> >> > >> >> > It sounds like you're interested in using auto generation for the ID >> >> value >> >> > instead of using System.currentTimeMillis(). You're in luck there as >> >> well. >> >> > OpenJPA supports several methods of auto generation which are >> discussed >> >> in >> >> > the manual [1]. >> >> > >> >> > The most simple way to use an auto generated id field would be this >> : >> >> > import javax.persistence.GeneratedValue; >> >> > >> >> > @Entity >> >> > @Table(name="produto") >> >> > public class Produto implements Serializable { >> >> > >> >> > @Id >> >> > @Column(name="id_produto") >> >> > @GeneratedValue >> >> > private int id; >> >> > . . . >> >> > } >> >> > >> >> > The GeneratedValue annotation causes OpenJPA to create an additional >> >> table >> >> > in the database which stores the last used ID value. Each new entity >> >> you >> >> > persist gets a new ID value which should be unique. This approach is >> >> > generic >> >> > and works on any of the supported databases. >> >> > >> >> > If you can't create a new table in the database then you'll probably >> >> want >> >> > to >> >> > use @GeneratedValue(strategy=GenerationType.IDENTITY) which tells >> the >> >> > Database to generate the ID value. It should work on most databases >> but >> >> > I've >> >> > only tried with DB2, MySQL, and Oracle. >> >> > >> >> > Hope this helps, >> >> > >> >> > -mike >> >> > >> >> > [1] >> >> > >> >> >> http://openjpa.apache.org/builds/latest/docs/manual/manual.html#jpa_overview_meta_gen >> >> > >> >> > On Tue, Oct 7, 2008 at 6:21 AM, thiago ananias >> >> > wrote: >> >> > >> >> >> >> >> >> Hello again! >> >> >> >> >> >> I'm need to make a classe that works in all databases, in the >> example >> >> of >> >> >> "Slice" the id is generated by "System.currentTimeMillis()" >> >> >> >> >> >> But i don't know if exists other way for map this class for oracle, >> >> >> sqlserver and mysql because there are differents kinds of >> >> ids(sequence, >> >> >> identity, auto). If don't exists a "universal mapping", i was >> thinking >> >> >> how >> >> >> can i generate a "UUDI" to be the ID of the tables, but how can i >> >> store >> >> >> this >> >> >> value in database? because if i store this value as string the >> >> database >> >> >> will >> >> >> be slow!! >> >> >> >> >> >> How can i make this class "universal" for the databases? >> >> >> >> >> >> @Entity >> >> >> @Table(name="produto") >> >> >> public class Produto implements Serializable { >> >> >> >> >> >> @Id >> >> >> @Column(name="id_produto") >> >> >> private int id; >> >> >> >> >> >> @Column(name="vc_nome", nullable=false) >> >> >> private String nome; >> >> >> >> >> >> @Column(name="dt_insert", nullable=false) >> >> >> @Temporal(javax.persistence.TemporalType.DATE) >> >> >> private Date dtInsert; >> >> >> >> >> >> >> >> >> } >> >> >> >> >> >> Thanks! >> >> >> >> >> >> -- >> >> >> View this message in context: >> >> >> >> >> >> http://n2.nabble.com/How-can-i-make-my-classes-work-in-all-databases--tp1303283p1303283.html >> >> >> Sent from the OpenJPA Users mailing list archive at Nabble.com. >> >> >> >> >> >> >> >> > >> >> > >> >> >> >> -- >> >> View this message in context: >> >> >> http://n2.nabble.com/How-can-i-make-my-classes-work-in-all-databases--tp1303283p1303755.html >> >> Sent from the OpenJPA Users mailing list archive at Nabble.com. >> >> >> >> >> > >> > >> >> -- >> View this message in context: >> http://n2.nabble.com/How-can-i-make-my-classes-work-in-all-databases--tp1303283p1306265.html >> Sent from the OpenJPA Users mailing list archive at Nabble.com. >> >> > > -- View this message in context: http://n2.nabble.com/How-can-i-make-my-classes-work-in-all-databases--tp1303283p1331788.html Sent from the OpenJPA Users mailing list archive at Nabble.com.
