Edition Based Redefinition: Online Application Upgrades Made Possible

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Edition Based Redefinition

Jérôme Witt
Consultant - Oracle Certified Professional 11g
Mobile +41 79 961 27 73
jerome.witt@dbi-services.com
www.dbi-services.com

1 www.dbi-services.com 08.11.2012 © dbi services

Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
iv. Redefining objects
v. Advanced functionalities
vi. Limits


Introduction

 Upgrading applications can be difficult
 Short or long downtimes can not be scheduled
 Implementation of online upgrades are desirable

 As of Oracle Database 11gR2 with Oracle Edition
Based Redefinition (aka. EBR) online application
upgrades are now supported

 Announced as “the killer feature” at the OOW 2009


Introduction

• Creation of new objects
Application upgrade

• Changing objects
(alter and create or replace)

• Drop redundant objects Downtime

EBR
• Convert or migrate data

• Resume normal operations


Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
vi. Limits


Concept(1)

 As of Oracle 11gR2 an object is identified by
 His name and the schema it belongs to
 And now also to an EDITION
SQL> desc DBA_OBJECTS
Name Null? Type
------------------ -------- ----------------
. . .
EDITION_NAME VARCHAR2(30)

 Allows to support several copies of an object
 Objects which might have copies are called “editioned objects”
 All other objects are “non editionable”


Concept (2)

 Which objects are “editionable” ?
 SYNONYM  All PL/SQL objects
 VIEW  PACKAGE and PACKAGE BODY
 PROCEDURE
 FUNCTION
 LIBRARY
 TRIGGER
 TYPE and TYPE BODY

 A non-editonable object cannot depend on an
editonable object


Concept(3)

 Editions are organized hierarchically «parent-child»

ORA$BASE ED1 ED2 ED3

• OBJ_1 • OBJ_1
• OBJ_2 • OBJ_2
• OBJ_3 • OBJ_3

ED2


Concept(4)

 Editions are organized hierarchically «parent-child»

ORA$BASE ED1 ED2 ED3

• OBJ_1 • OBJ_1
• OBJ_2 • OBJ_2
• OBJ_3 • OBJ_3

 Inheritance
 When an edition is created all objects associated with the parent
are inherited by the child. They become «inherited»
 Objects re-created or altered in an edition become “actualized”
(i.e. objects OBJ_2 & OBJ_3 of the edition ED3)
 Inherited & actual objects are “visible”

Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
vi. Limits


Basics (1)

 Creating editions
 Database default edition «ORA$BASE»
 Database creation or upgrade to Oracle 11.2
 Has no actual editioned objects
SQL> CREATE EDITION <ed_name> {AS CHILD OF ora$base};

 Enabling editions
SQL> ALTER USER <schema> ENABLE EDITIONS {FORCE};
 Editioned objects can only be owned by schemas that have
been explicitly enabled
 FORCE if schema has potentially editionable objects
 By the way DISABLE EDTIONS doesn’t exists !


Basics (2)

 Granting editions
SQL> GRANT USE ON EDITION <ed_name> TO <schema>;

 Selecting editions
SQL> ALTER SESSION SET EDITION =<ed_name>;

 Retrieving current and session edition
SQL> SHOW EDITION;

SQL> SELECT
SYS_CONTEXT('USERENV', 'CURRENT_EDITION_NAME'),
SYS_CONTEXT('USERENV', 'SESSION_EDITION_NAME')
FROM dual;


Basics (3)

 Enabling an edition database wide
SQL> ALTER DATABASE DEFAULT EDITION=<ed_name>;

SQL> SELECT property_value FROM database_properties
WHERE property_name = 'DEFAULT_EDITION';

 Selecting edition at connection time
DBMS_SERVICE.CREATE_SERVICE(
service_name => '<ORACLE_SID.DB_DOMAIN>',
. . .
edition => '<ed_name>');

 EBR integrated with
 Oracle Call Interface  JDBC
 Oracle Restart (srvctl)

Basics (4)

 Display all database editions
 Views {DBA|ALL}_EDITIONS

 Display all objects editions
 Views {DBA|ALL|USER}_OBJECTS_AE

 View current edition from an object
 Views {DBA|ALL|USER}_OBJECTS.EDITION_NAME

 And so on …


Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
vi. Limits


Redefining objects(1)

SQL> BEGIN
raiseSalary(
p_title_in => 'COM_DBISERVICES . . . ',
p_rate_in => 1.10,
p_max_sal_in => 50000 );
END;
/



PROCEDURE raiseSalary(. . .) IS
. . .
CURSOR cur_emp IS SELECT * FROM EMPLOYEES FOR UPDATE;
BEGIN
OPEN cur_emp;
LOOP
FETCH cur_emp INTO rec_emp;
. . .
SELECT upper(job_title) INTO v_cur_title FROM hr.jobs
WHERE job_id = rec_emp.job_id;
IF v_cur_title = v_title_in
AND rec_emp.salary*p_rate_in <= p_max_sal_in
THEN
-- Do some other checks on employee
UPDATE . . .
END IF;
END LOOP;
CLOSE cur_emp;
COMMIT;
END;


PROCEDURE raiseSalary(. . .) IS
. . .
CURSOR cur_emp IS
SELECT e.employee_id from hr.employees e, hr.jobs j
WHERE e.job_id = j.job_id AND upper(j.job_title) = v_title_in
AND e.salary*p_rate_in <= p_max_sal_in;
BEGIN
OPEN cur_emp;
LOOP
FETCH cur_emp BULK COLLECT INTO v_empid_list LIMIT 1000;
EXIT WHEN v_empid_list.COUNT = 0;

-- Do some other checks on employee
FORALL i IN v_empid_list.FIRST .. v_empid_list.LAST
UPDATE hr.employees SET salary=salary*p_rate_in
WHERE employee_id=v_empid_list(i);

END LOOP;
CLOSE cur_emp; COMMIT;
END;


 Typical EBR redefinition steps
1. Create the new edition
2. Set the edition as session edition
3. Redefine the objects
4. Permanently switch to the new edition

 To “redefine” objects it’s necessary to select the new
edition and either re-compile or recreate objects

 Consider application roll out strategy


Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
vi. Limits


Advanced functionalities(1)

 Views
 Editionable (of course)
 Support only INSTEAD OF triggers

 Editioning views
 Selects a subset of the columns from a single base table
 Optionally, provide aliases for columns
 Doesn’t support indexes nor constraints
 No performance penalty for accessing base table
 Support any type of triggers
(especially CROSSEDITION TRIGGERS)
SQL> CREATE EDITIONING VIEW <name> AS SELECT ...;



 Crossedition triggers
 Propagate data changes made by the old edition into the new
edition’s columns, or vice-versa.
 From type FORWARD or REVERSE
 They are temporary!

SQL> CREATE OR REPLACE TRIGGER <trigger_name>
BEFORE INSERT OR UPDATE ON <table_name>
FOR EACH ROW
FORWARD CROSSEDITION
DISABLE
BEGIN
. . .
END <trigger_name>;
/



New Edition : ED_V1
C_Pool
ED_V1 EMPLOYEES
First Last Phone
Name Name Nbr

EMPLOYEES_TAB
EMPLOYEES
First Last Phone
Name Name Nbr



ED_V2
New Edition : ED_V1
C_Pool
ED_V1 EMPLOYEES
EMPLOYEES
First First Phone
Last Last Phone
Dial Int
Name Name
Name Name
Nbr Nbr PhNbr
Code

FWD_TRG

REV_TRG

EMPLOYEES_TAB
EMPLOYEES_TAB
First First Phone
Last Last Phone Int
Dial
Name Name Nbr
Name Name Code
Nbr PhNbr



New Edition : ED_V2
C_Pool
ED_V1 EMPLOYEES
First Last Phone Dial Int
Name Name Nbr Code PhNbr

FWD_TRG

REV_TRG

EMPLOYEES_TAB
C_Pool
ED_V2 First Last Phone Dial Int
Name Name Nbr Code PhNbr



 Hot roll-over “bulk forward”
 Wait for pending DMLs
DBMS_UTILITY.WAIT_ON_PENDING_DML(
tables => '<Base_Table>',
timeout => timeout,
scn => scn
);

 Apply transformation
DBMS_SQL.PARSE(
c => c,
Language_Flag => DBMS_SQL.NATIVE,
Statement=> 'UPDATE employees SET ID = ID',
Apply_Crossedition_Trigger => '<CRED_TRG_FWD>'
);


Agenda

Agenda
i. Introduction
ii. Concept
iii. Basics
vi. Limits


Limits

 Performance & Tuning
 Indexes & constraints must be added to the base table
 To limit negative performance impact specify an INDEX hint
within the crossedition triggers
 Editioning views accept SQL optimizer hints
 Logical column names must be mapped to an index on the
corresponding physical column in the base table
SQL> SELECT /*+ INDEX (edview1 idx1)*/ email
FROM edview1 WHERE last_name='King';

 Can not drop retired editions!
 Bugs (11.2.0.3) – do not drop edition ORA$BASE
 One of the least known Oracle database feature

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Any Questions? Please Do Ask!

Jérôme Witt
Consultant - Oracle Certified Professional 11g
Mobile +41 79 961 27 73
jerome.witt@dbi-services.com
www.dbi-services.com

„We look forward to working with you!“


Edition Based Redefinition: Online Application Upgrades Made Possible

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