Edition-based redefinition (EBR) in Oracle Database 11g Release 2 is spectacular, introducing a new dimension to the database which allows us to version objects within a schema. Through EBR, we achieve zero-downtime application upgrade and multiple application versions simultaneously against one schema. No more big-bang upgrade! This session introduces EBR, demonstrates the SQL, and shows the multi-version application. It dives into some complexities of data synchronization between editions and discusses best practices with EBR.

1. Release 2 Release 3 Base Release Introducing and Demonstrating Oracle Database 11gR2's Killer FeatureEdition- Based Redefinition for Developers and DBAs ODTUG Kaleidoscope 2010 Lucas Jellema AMIS, The Netherlands

2. The Book Application - Version 1

3. Application Version 1 on Database Edition Release 2

4. Database Upgrade Base release to Release 2 Authors New columns COUNTRY and BIOGRAPHY Books Drop column NUM_OF_PAGES Modified column ISBN (10 to 20 characters) New columns LANGUAGE and PUBLICATION_YEAR

5. Application Version 2 (on Database Edition Release 2)

6. Application Version 2 on Base Edition in the Database

7. Release 2 Base Release ALS Schema

8. Availability Availability = Performance * (Up or Down) Up = !Down Down = Unplanned Down + Planned Down Planned Down??? System Maintenance Power-supply, Hardware & Network, O/S upgrade Database patching & Upgrade Application Upgrades

9. Maximum Availability Architecture

10. Application Upgrade Creation of new objects Changing existing objects (alter and create or replace) Add, Modify or Drop columns or constraints Change packages and stored procedures Recompile Drop redundant objects Convert or migrate data Resume normal operations Application is DOWN

11. Compare with road maintenance

12. Restructuring A12 Build new road next to current one (A12-B) Same “functionality” as the old road At the cut-over moment Open new A12-B: Newly arriving traffic travels on temporary road Close A12 (original) Cars already on old road keep going

13. 11gR2 Editioning is similar Application Upgrade: Prepare new release Construct the release in parallel to the existing Operations in existing application ‘edition’ continue normally From the cut-over point: Have new sessions operate on new release Existing sessions can continue to run on existing release

14. 11gR2 Editions introduces a new dimension in the database Release 3 Release 2 Base Release

15. Editions introduce or inherit versions of objects Release 2 Release 3 Base Release

16. Editions are parallel universes Database Objects are identified by Object Type Schema Object Name …. Edition! (release, application version, stripe, parallel universe id) Database Sessions run in the context of a specific edition Using a specific collection of versions of objects

17. Database sessions run in a specific edition –one version of each object Release 2 Release 3 Base Release The database as seen by a sessionrunning in the context of Release 3 3 2 3 B 2 2 3 3 2

18. Release 2 Base Release ALS Schema

19. Parallel Application Versions Application X VERSION 1 Application X VERSION 2 Release 2 Release 3 Base Release

20. The end of the big bang After the release of a new edition – there is no reason why you cannot keep the previous one going for some time And multiple previous ones! That means – END OF THE BIG BANG upgrade! Multiple versions of the application can continue running to support various user groups (e.g. SaaS) Without data migration and additional downtime upon later move over of user groups

21. Demo of Database Editions Existing base application, in base edition Create new edition – release_2 Create and Alter database objects Base application continues running Cut-over point New sessions run in release_2 edition Current sessions continue in base

22. CONNECT SYS/ORACLE as SYSDBA CREATE EDITION release_2; CREATE EDITION release_3 AS CHILD OF release_2; SELECT * FROM DBA_EDITIONS; CREATE USER SCOTTY identified by tiger; ALTER USER SCOTTY ENABLE EDITIONS FORCE GRANT USE ON EDITION release_2 TO SCOTTY CONNECT SCOTTY/TIGER ALTER SESSION SET EDITION = ORA$BASE CREATE OR REPLACE FUNCTION HELLO_WORLD ALTER SESSION SET EDITION = RELEASE_2 CREATE OR REPLACE FUNCTION HELLO_WORLD ALTER SESSION SET EDITION = RELEASE_3 DROP FUNCTION HELLO_WORLD Release 2 Release 3 Base Release 2 1 X

23. Some Rules for EBR (Edition Based Redefinition) EBR acts on packages, functions, triggers, procedures, views, types and synonyms EBR does not apply to tables Data is not versioned, cloned, migrated Different incarnations of a table are suggested through editioningviews – there is only one table Applications should never access tables directly!

24. Editions and Tables Tables cannot be versioned: there is only one definition of a table across all Editions Data is not versioned: a record exists once and only once The solution for managing changes to Tables: Editioning Views and Cross Edition Triggers Editioning Views are defined on base table (no joins) Editioning Views can have DML triggers defined (just like base table) Using an editioning view in a query or DML statement does not impact the performance of the query or DML

25. Editions and Tables Application A Application B Table EMP SAL MGR JOB ENAME HIREDATE COMM

26. Editions and Tables Application A Application B Editioning View EMP Table EMP_BASE SAL MGR JOB ENAME HIREDATE COMM

27. Oracle guarantees:The Execution Plan for a SQL query that uses an Editioning View is identical to that for the same query based directly on the table

28. Migrate to Editioning Views Rename Table (for example to <old table name>_BASE) Constraints continue to refer to the table Create the Editioning View with the old table name Using the ‘CREATE OR REPLACE EDITIONING VIEW <view name>’ statement Reroute privileges – grant on view rather than table Recompile the triggers on the table These now become triggers on the Editioning View Recompile all invalid PL/SQL program units and Views They now refer to the Editioning View instead of the table VPD policies are reassigned to the View Regular auditing and FGA is on the table

29. Demo ALTER TABLE EMP RENAME TO EMP_BASE; CREATE OR REPLACE EDITIONING VIEW EMP AS SELECT ... FROM EMP_BASE / DROP TRIGGER EMP_BRI / Rem recreate trigger on Editioning View @<EMP_BRI>.trg Rem recompile invalid Views and PL/SQL units

30. Multiple versions of Editioning View Application A Application B Edition R2 Edition R1 Editioning View EMP Editioning View EMP Table EMP_BASE SAL MGR JOB ENAME HIREDATE COMM

31. Multiple versions of Editioning View Application A Application B Edition R2 Edition R1 View EMP (1.1) …* Language View EMP (1.0) Table EMP_BASE SAL MGR JOB ENAME LANGUAGE HIREDATE COMM Forward CrosseditionTrigger

32. Demo CREATE EDITION R2 AS CHILD OF R1; ALTER SESSION SET EDITION R2; SHOW EDITION ALTER TABLE EMP_BASE ADD (LANGUAGE VARCHAR2(2) NULL); Rem function for deriving value for language CREATE OR REPLACE FUNCTION GET_LANGUAGE( p_job in varchar2) return varchar2 is begin return case p_job when 'MANAGER' then 'fr' else 'en' end; end;

33. Demo Rem Create Forward Crossedition Trigger Rem Applies to DML operations on EMP_BASE from Rem Earlier Editions CREATE OR REPLACE TRIGGER EMP_1_1_Fwd_Xed BEFORE INSERT OR UPDATE ON EMP_BASE FOR EACH ROW FORWARD CROSSEDITION DISABLE BEGIN :new.language = get_language(:new.job); END EMP_1_1_Fwd_Xed; Rem Enable the Forward Crossedition Trigger ALTER TRIGGEREMP_1_1_Fwd_Xed ENABLE;

34. Demo Rem Use Forward Crossedition trigger to Rem upgrade existing table records according to new table Rem version (for large # records use dbms_parallel_execute) DECLARE c NUMBER := DBMS_SQL.OPEN_CURSOR(); x NUMBER; BEGIN DBMS_SQL.PARSE ( c => c , Language_Flag => DBMS_SQL.NATIVE , Statement => 'UPDATE EMP_BASE SET EMPNO = EMPNO' , Apply_Crossedition_Trigger => 'EMP_1_1_Fwd_Xed' ); x := DBMS_SQL.EXECUTE(c); DBMS_SQL.CLOSE_CURSOR(c); COMMIT; END;

35. Upgrade Table Definition Make desired changes to the table Add columns, modify Columns, … (online redefinition) (Create Edition,) Set target Edition for session Modify the Editioning View in the Edition To reflect the table as its latest version should look Perhaps hiding columns you eventually want to drop (optional) Create Forward Crossedition Trigger on base table to have DML on previous Editions made valid (optional) Create Reverse Crossedition Trigger on base table to have DML on current Edition synch back

36. Cross Edition Triggers If you remove a (mandatory) column from the current Editioning View… a Reverse Crossedition Trigger ensures that new records get some value in that (invisible) column If you add a (mandatory) column to the table (and the current Editioning View)… a Forward Crossedition Trigger ensures that records DMLed through previous Editioning View versions are made valid (optionally) Apply Forward Crossedition Trigger for all existing records (created in old edition of the table) Use DBMS_SQL.parse (with parameter Apply_Crossedition_Trigger set to name of trigger) Use DBMS_PARALLEL_EXECUTE

37. Multiple versions of Editioning View Application A Application B Edition R3 View EMP (1.1) … (minus ENAME)* Language o FIRST_NAME * LAST_NAME Edition R1 Edition R2 View EMP (1.1) …* Language View EMP (1.0) Table EMP_BASE Reverse Crossedition Trigger SAL MGR JOB ENAME LANGUAGE FIRSTNAME LASTNAME HIREDATE COMM Forward CrosseditionTrigger

38. “Suggested (best) Practices” Every application (release) sets the Edition it requires when it connects to a session At the same time it calls dbms_application_info And sets other Context details Note: you could use multiple database service definitions to access the same database For example: ORCL_BASE, ORCL_R2, ORCL_R3 JEE data sources can be configured for a specific service A logon trigger can read the service name used to connect to the database and set edition accordingly

39. “Suggested (best) Practices” Applications should never access tables – all access should be through views Only through views can the data structure itself be Editioned Even triggers should be on the EditioningView Except cross edition triggers

40. Replacement Table Pattern Application A Application B Edition R2 Edition R1 EditioningView APP_DATA EditioningView APP_DATA Table APPLICATION_METADATA APPLICATION_METADATA_R2 ORGID USER VALUE KEY Default ORGID USER VALUE KEY Default

41. Alternative Approach for Data Versioning Application A Application B Edition R2 Edition R1 View DATA select *from EDITIONED_DATAwhere <current_edition> betweenas_of_edition anduntil_edition Table EDITIONED_DATA * as_of_edition * until_edition … normal columns

42. Interesting EBR Tid-Bits Drop Object in an Edition stops the inheritance from previous Edition. Object no longer is carried forward Edition can have only one child – no branches (yet) DBMS_SQL.PARSE can be executed in a specific Edition Use parameter edition to specify other than current edition If no explicit edition is set for a session, the default edition is used ALTER DATABASE DEFAULT EDITION = edition_name; Hints in queries against Editionable Views are understood in terms of the underlying table Logical EV column references are correctly mapped

43. Interesting EBR Tid-Bits DB Links & Materialized Views currently not editionable Objects of an editionable type are not editionable when used by a non-editionableobject PL/SQL Function used in Function Based Index or the definition of a Materialized View ADT used as the base type for a column in a table Data Dictionary Views DBA_/ALL_EDITIONS – editions in the database DBA_/ALL_OBJECTS – objects (inherited) in current edition DBA_/ALL_OBJECTS_AE – actual objects across all editions

44. Summary 11gR2 Editions are parallel, co-existing universes with incarnations of database objects The new release can be constructed, tested and run in a new edition The old edition can be switched off at cut-over Editions also allow long time co-existence of multiple releases of an application Application Upgrade no longer needs to disrupt the operation through planned downtime By the way: EBR is available in all DB editions

45. Conclusion See our blog for Oracle Database 11gR2 articles (other topics as well) http://technology.amis.nl/blog This presentation and the demo scripts are on the blog too Contact me: lucas.jellema@amis.nl