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Oracle Database's Edition-Based Redefinition

Oracle Database's Edition-Based Redefinition Seminar

April 3, 2019 - 09:00 - 17:00

In general, patching or upgrading the artifacts in an Oracle Database that jointly implement an application’s back end involves changing two or more functionally dependent objects. Because each DDL autocommits, such changes inevitably imply that the system is mutually inconsistent once the patching begins and that its integrity is regained only when patching completes. Moreover, so-called “hot patching”—doing create or replace on even a single object, while that object is among the set of objects in ordinary concurrent use by the application, is in general unsafe. Before EBR, your only option, therefore, was to take downtime. EBR allows you to create a semantic copy of the live system within the same database so that you can make your changes to this while the live system remains in uninterrupted use. A copy-on-write scheme is used so that only changed objects occupy space. Of course, the quota-consuming data must be mutually synchronized, transactionally, and without harming performance for ordinary users. EBR supports this too. This workshop explained how it all works.

Agenda Items

  • The conceptual challenges implied by the zero-downtime application patching goal
  • The core teaching
  • Explaining the SQL statements that implement an EBR exercise
  • Final round of questions, discussions and summary





Bryn Llewellyn

Distinguished Product Manager

Database Server Technologies Division, Oracle HQ

Bryn has worked in the software field for more than forty years. He joined Oracle UK in 1990 at the European Development Center to work on the Oracle Designer team. He transferred to the Oracle Text team and then into consulting as the Text specialist for Europe. He relocated to Redwood Shores in 1996 to join the Oracle Text Technical Marketing Group. He has been the product manager for PL/SQL since 2001. In 2005, he became responsible, additionally, for edition-based redefinition (EBR for short). This is the Oracle Database capability that supports zero downtime application upgrade.




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