Hotsos Symposium Speaker – Bryn Llewellyn

Mr. Llewellyn is a returning Hotsos Symposium presenter.


Bryn LlewellynBryn has worked in the software field for 30 years. He joined Oracle UK in 1990, at the European Development Center, to work in 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 became the Product Manager for PL/SQL in 2001. And in 2005, his product management brief expanded to include the Oracle Database capabilities (then not yet generally available) that support online application upgrade. It's hard for Bryn to remember his life before Oracle. He started off doing image analysis and pattern recognition at Oxford University (programming in FORTRAN!) and then worked in Oslo, first at the Norwegian Computing Center and then and in a startup. In Norway, Bryn programmed in Simula (its inventors were his close colleagues). This language is recognized the first object-oriented programming language and was the inspiration for Smalltalk and C++.

Presentation Title

Edition-Based Redefinition: the Key to Online Application Upgrade


Large, mission-critical applications built on Oracle Database are often unavailable for tens of hours while the application's database objects are patched or upgraded. Oracle Database 11g Release 2 introduces revolutionary new capabilities that allow online application upgrade with uninterrupted availability of the application. Existing sessions can continue to use the pre-upgrade application until their users decide to finish; and, at the same time, new sessions can use the post-upgrade application. When no sessions are any longer using the pre-upgrade application, it can be retired. The application as a whole therefore enjoys hot rollover from the pre-upgrade version to the post-upgrade version.

The capability depends on these new kinds of object: the edition, the editioning view, and the crossedition trigger. Code changes are installed in the privacy of a new edition. Data changes are made safely by writing only to new columns or new tables not seen by the old edition. An editioning view exposes a different projection of a table into each edition to allow each to see just its own columns. A crossedition trigger propagates data changes made by the old edition into the new edition's columns, or (in hot-rollover) vice-versa. The capability as a whole is called edition-based redefinition -- EBR for short.

This session explains how it all works.

Presentation Materials

Presentation materials are available online to attendees only.


The speaker schedule is as follows: