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Difference between revisions of "EclipseLink/Examples/JPA/TemporalEntity"
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=== Create Person Edition == | === Create Person Edition == | ||
Revision as of 16:04, 20 October 2011
EclipseLink JPA Futures Example
This example is intended to illustrate how entity versions can be stored and queried in a database. Unlike the history functionality of EclipseLink this example is focused on creating versions of an entity that may take effect in the future.
Requirements
- Optimize queries against current version. Queries against future versions
- Allow versions for the future to be created with a time they are expected to become the current
- When a future version is promoted to current its temporal storage is not required (no history remains)
- Allow multiple future versions and support changing when a future version takes effect
- Support defining a new entity that does not yet exist but may exist in the future
Software
This example is being built using EclipseLink 2.3.1. To access the source of the example check it out of SVN at:
/svnroot/rt/org.eclipse.persistence/trunk/examples/org.eclipse.persistence.example.jpa.futures
How it Works
Coming Soon...
Examples
The following examples are from test cases.
Schema Generation
At the start of each test suite the schema is replaced. The resulting CREATE TABLE operations are:
CREATE TABLE TPERSON (OID NUMBER(10) NOT NULL, END_TS NUMBER(19) NULL, F_NAME VARCHAR2(255) NULL, L_NAME VARCHAR2(255) NULL, START_TS NUMBER(19) NULL, CID NUMBER(10) NULL, ADDRESS_OID NUMBER(10) NULL, PRIMARY KEY (OID)) CREATE TABLE TADDRESS (OID NUMBER(10) NOT NULL, CITY VARCHAR2(255) NULL, END_TS NUMBER(19) NULL, START_TS NUMBER(19) NULL, STATE VARCHAR2(255) NULL, STREET VARCHAR2(255) NULL, CID NUMBER(10) NULL, PRIMARY KEY (OID)) ALTER TABLE TPERSON ADD CONSTRAINT FK_TPERSON_ADDRESS_OID FOREIGN KEY (ADDRESS_OID) REFERENCES TADDRESS (OID) ALTER TABLE TPERSON ADD CONSTRAINT FK_TPERSON_CID FOREIGN KEY (CID) REFERENCES TPERSON (OID) ALTER TABLE TADDRESS ADD CONSTRAINT FK_TADDRESS_CID FOREIGN KEY (CID) REFERENCES TADDRESS (OID)
Create Current Person
Person p = new Person(); p.setFirstName("Doug"); p.setLastName("Clarke"); Address a = new Address(); a.setStreet("45 O'Connor Street"); a.setCity("Ottawa"); a.setState("Ontario"); p.setAddress(a); em.persist(a); em.persist(p);
Resulting SQL:
[EL Fine]: INSERT INTO TADDRESS (OID, CITY, END_TS, START_TS, STATE, STREET, CID) VALUES (?, ?, ?, ?, ?, ?, ?) bind => [1, Ottawa, 9223372036854775807, 0, Ontario, 45 OConnor Street, NULL] [EL Fine]: UPDATE TADDRESS SET STATE = ?, STREET = ?, CID = ?, CITY = ? WHERE (OID = ?) bind => [Ontario, 45 OConnor Street, 1, Ottawa, 1] [EL Fine]: INSERT INTO TPERSON (OID, END_TS, F_NAME, L_NAME, START_TS, CID, ADDRESS_OID) VALUES (?, ?, ?, ?, ?, ?, ?) bind => [2, 9223372036854775807, Doug, Clarke, 0, NULL, NULL] [EL Fine]: UPDATE TPERSON SET CID = ?, ADDRESS_OID = ?, F_NAME = ?, L_NAME = ? WHERE (OID = ?) bind => [2, 1, Doug, Clarke, 2]
Note: The INSERT followed by the UPDATE statement are to populate the self-referencing FK values. Optimized solution being investigated
= Create Person Edition
This example creates an edition of a current Person (id={currentPersonId}) which is set to take effect at T2 and be deleted or replaced at T4. The current version of the person is updated accordingly to end at T2.
Person currentPerson = em.find(Person.class, currentPersonId); Person p = TemporalHelper.createEdition(em, currentPerson); p.setFirstName("Dougie"); p.setStart(T2); currentPerson.setEnd(T2); p.setEnd(T4); em.persist(p);
SQL:
...Create Future Person
This creates a new Person that does not currently exist but will exist as of T3.
Person p = new Person(); p.setFirstName("John"); p.setLastName("Doe"); p.setStart(T3); em.persist(p);
SQL:
[EL Fine]: INSERT INTO TPERSON (OID, END_TS, F_NAME, L_NAME, START_TS, CID, ADDRESS_OID) VALUES (?, ?, ?, ?, ?, ?, ?) bind => [1, 9223372036854775807, John, Doe, 3, NULL, NULL] [EL Fine]: UPDATE TPERSON SET CID = ?, START_TS = ?, F_NAME = ?, L_NAME = ? WHERE (OID = ?) bind => [1, 3, John, Doe, 1]
Query for Current Person
SQL:
Find Current Person
Person person = em.find(Person.class, currentPersonId); System.out.println("FIND CURRENT: " + person);
LOG:
[EL Fine]: SELECT OID, CITY, END_TS, START_TS, STATE, STREET, CID FROM TADDRESS WHERE ((OID = ?) AND (START_TS = ?)) bind => [1, 0] FIND CURRENT: model.Person(2)::Doug @ 0-2
Query all Current Persons
List<Person> results = em.createQuery("SELECT p From Person p", Person.class).getResultList();
LOG:
[EL Fine]: SELECT OID, END_TS, F_NAME, L_NAME, START_TS, CID, ADDRESS_OID FROM TPERSON WHERE (START_TS = ?) bind => [0]
Find Person edition @ T3
Map<String, Object> props = new HashMap<String, Object>(); props.put("EFF_TS", T3); EntityManager em = emf.createEntityManager(props); Person personEdition = em.createQuery("SELECT p From PersonEdition p WHERE p.cid = " + currentPersonId, Person.class).getSingleResult(); System.out.println("QUERY EFFECTIVE @ T3: " + personEdition);
Log Output:
[EL Fine]: SELECT OID, END_TS, F_NAME, L_NAME, START_TS, CID, ADDRESS_OID FROM TPERSON WHERE ((CID = ?) AND ((? >= START_TS) AND (? < END_TS))) bind => [2, 3, 3] QUERY EFFECTIVE @ T3: Person(3)::Dougie @ 2-4