Posts tagged edition based redefinition
Availability is a highly desirable aspect of Fusion Middleware application. Planned downtime therefore sounds quite silly. However, the introduction of changes to applications has typically been associated with the roll out and redeployment of the application causing disruption of service – through loss of existing conversations and unavailability during the deployment process. Several approaches and mechanisms are available in the Oracle stack that will help substantially reduce the loss of uptime because of changes to applications.
First of all, many types of changes may be implemented through run time configuration, rather than software change requiring redeployment of application artifacts. This approach requires good design of aspects of applications that may require modification and the construction of run time mechanisms for applying and processing such changes. The design time at run time capabilities of several Fusion Middleware products go a long way in supporting this approach.
Additionally, several FMW components support short or even long term co-existence of different versions of applications. This means that existing conversations can complete even when a new More >
OOW 2009: The killer feature of Oracle Database 11gR2 – Edition Based Redefinition (or database object versioning)
Today I presented on what is possibly the hottest story on the Oracle Database 11gR2 release: Edition Based Redefinition (EBR). EBR allows us to add a whole new dimension to the database – the Edition (that complements the existing dimensions of schema and object type). Every database object (well, almost every database object – not tables!) can have different implementations/incarnations/versions in various editions. The object versions are all in the same schema – they only differ in the Edition they are created in.
The Edition Based Redefinition has us create Editions in the database – cross database object spaces where new versions of existing database objects can be created – and others can just be inherited from previous editions. We can construct an Edition in isolation – no one is impacted by us creating new objects and versions of objects; objects can be invalid in that edition and no one will know anything about it. Only once the edition is complete, valid and tested can we make it available to new user sessions to work against. Using a simple alter session set edition statement, sessions can specify which edition they want to run against. That is: after the user has More >
One of the most spectacular new facilities in Release 2 of the Oracle 11g Database is called Edition Based Redefinition – not a name perhaps that suggests any spectacle. EBR (Edition Based Redefinition) is a mechanism that allows on line application upgrade with no planned downtime. In short, the new release is built up in parallel to the existing one, in the same schema and using the same database objects; only the new (modified) objects live in another dimension and do not impact the existing objects. Once the entire set of new and changed objects has been created and recompiled, the database administrator can start routing new sessions to the new release; existing sessions can continue to run against the original set of objects – and new sessions if so desired can also run against the orginal set.
A set of object versions – mutually consistent and interdependent – which in software engineering terms would be duped a release or stripe and in Oracle Software Configuration Manager (Designer) terms a configuration is called an edition in 11gR2 lingo. An Edition is a combination of new objects, new versions of objects and inherited pre-existing versions that together make up a More >