how to upgrade your application with no downtime (using edition-based redefinition)

How to Upgrade Your Application with no Downtime(and no Additional Costs!)

Oren Nakdimon

www.db-oriented.com

[email protected]

+972-54-4393763

@DBoriented

This presentation is available in http://db-oriented.com/presentations © O

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WHO AM I?A CHRONOLOGY BY “ORACLE YEARS”

Where: IAF

When: Oracle 6/7 [1991-1997]

What: Developer Where: Golden Screens

When: Oracle 8 [1997-1998]

What: Server Group ManagerWhere: TELEknowledge

When: Oracle 8i/9i [1998-2003]

What: DBA Group Manager

Where: Olista

When: Oracle 10g/11g [2004-2011]

What: VP R&D + Israel Site Manager

http://db-oriented.com/presentations


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WHO AM I?A CHRONOLOGY BY “ORACLE YEARS”

Database Architect /

Developer / DBA



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@DBORIENTED



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HTTP://DB-ORIENTED.COM



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SHARING EXPERIENCE FROM…

A 24x7 system

Millions of end-users

Thousands of concurrent end-users

All around the world

Lots of PL/SQL code

Frequent upgrades

Intensive use of EBR



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THE BOTTOM LINE

I think EBR is great!

It is quite a big and complex feature, but…

It is very easy to start using it

It may take some time to know all the details and nuances

Warning: as with any other feature, make sure to test it thoroughly before you decide to apply it in production



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AGENDA

Application upgrades

Scenarios

Methods

EBR introduction

Upgrade use cases

Requirements

Challenges with online upgrade

Solving with EBR

Tips


APPLICATION UPGRADES

Scenarios


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Application XApplication X

+ some change(s)



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Upgrades are inherent to every application lifecycle

They may be:

Small or big

Frequent or rare

Simple or complex

With or without schema changes

Introducing new functionality, changing existing functionality, or removing functionality



Methods

EDITION-BASED REDEFINITION

Introduction


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EDITION BASED REDEFINITION

EBR is a feature set that lets you upgrade the database component of an application while it is in use, thereby minimizing or eliminating downtime

Introduced in 11gR2

EBR is supported in all editions, and requires no special license



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The fundamental ability is that different copies of the same object may coexist

Not all objects are editionable

EDITION BASED REDEFINITION

Edition1

Edition2

PKG_A

JERRYTOM

PKG_A

PKG_A

MY_VIEW

MY_VIEW

MY_OBJ

MY_OBJ

TABLE_X TABLE_Y



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EDITIONS

Edition is a non-schema object

There must be at least one edition in the database

The initial edition is ORA$BASE

There is always one database-level default edition



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EDITIONS – CONT.

Every new edition is created as a child of an existing edition

Currently (11.2, 12.*), each edition may have at most one child edition

Edition1

Edition2

Edition3Edition3b


UPGRADE USE CASES


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PEOPLE

(table)

PEOPLE_DL

(package)

add | remove

APP_MGR

(package)

do_something



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S B S B Table

APP_MGR PEOPLE_DL

@people_setup



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USE CASE 1 – THE REQUIREMENTS

A package body should be changed

No change in package spec

No change in table structure



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USE CASE 1 – THE CHALLENGES

Blocking

Compilation is blocked by active clients

Clients are blocked during compilation

begin

p;

end;

/

alter procedure p compile;

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

begin

p;

end;

/

Session 1

Session 2

Session 3



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EDITIONS AND USERS

To be able to own editioned objects

Editioning must be enabled for the user

ALTER USER user ENABLE EDITIONS [FOR type…];

This is an irreversible operation

This is a retroactive operation

@enable



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EDITIONS AND USERS – CONT.

To be able to use a specific edition

Users must be granted the USE privilege on the edition

GRANT USE ON EDITION edition TO user;

PUBLIC is always granted the database default edition

@grant



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SESSION EDITION

Each session uses one edition at a time

The current session edition:

SHOW EDITION (SQL*Plus)

SYS_CONTEXT('userenv', 'session_edition_name')

To change the session edition:

ALTER SESSION SET EDITION = edition;

Must be the first statement of a transaction



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EDITIONED OBJECTS

An editioned object in an edition is either:

Inherited

or

Actual

Note: actualization is irreversible!

@end_user_session

@use_case_1

p edition1

edition2

edition3p



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S B S B

Table

ora$base

APP_MGR PEOPLE_DL

V1 B



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A package spec should be changed


S B S B

Table

ora$base

APP_MGR PEOPLE_DL

V1 B



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Invalidation

Compilation errors (hopefully not…)

Object dependency Revalidation occurs automatically when an object is

referenced

Multiple interrelated objects need to be changed

S B S B

Table

APP_MGR PEOPLE_DL



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USE CASE 2



S B S Bora$base

APP_MGR PEOPLE_DL

V1 B

V2 S

Table



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USE CASE 2



@use_case_2

S B S Bora$base

APP_MGR PEOPLE_DL

V1 B

V2 S

Table

B B



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A VERY IMPORTANT FOOTNOTE

Source: http://www.oracle.com/technetwork/database/features/availability/ebr-455513.html


http://www.oracle.com/technetwork/database/features/availability/ebr-455513.html


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A new column should be added

It represents a new logic

An existing package should be changed accordingly



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Invalidation

Code dependent on the table is invalidated (!)

S B S B

Table

ora$base

APP_MGR PEOPLE_DL

V1 B

V2 SB B



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ViewProgram

Unit

ELIMINATING INVALIDATION

Table



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EDITIONING VIEWS

Editioning Views are:

Views (hence editionable)

Deliberately limited:One per table

May contain only the SELECT and FROM clauses

The FROM clause refers to a single table

The SELECT list may contain only columns and aliases (no expressions), and each column may appear only once

Or in short: the view subquery may only project columns of its base table and aliasing the projected columns

DML triggers can be defined on them



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Editioning Views are

the Interface

between the

Application and the

Tables



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@use_case_3

Tip



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It replaces an existing column

Cutover

@use_case_4



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Keeping the old representation and new representation in sync until the cutover



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CROSSEDITION TRIGGERS

A crossedition trigger is a “bridge” for moving data between editions

Temporary in nature

Forward crossedition triggers transform pre-upgrade representation to post-upgrade representation

@fce_trigger



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USE CASE 5


It replaces an existing column

Rollover



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REVERSE CROSSEDITION TRIGGERS

Reverse crossedition triggers transform post-upgrade representation to pre-upgrade representation

@rce_trigger



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EXPOSING THE NEW VERSION

Database-level:

ALTER DATABASE DEFAULT EDITION = edition;

Session level

Statement level – using DBMS_SQL.PARSE

Service level


THANK YOU

Oren Nakdimon

www.db-oriented.com

[email protected]

+972-54-4393763

@DBoriented

how to upgrade your application with no downtime (using edition-based redefinition)

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