Edition-Based Redefinition

Upgrading critical applications can be very difficult. One of the main problems is that for reasons of availability, long downtimes cannot be periodically scheduled. Therefore, for such applications, it is desirable to implement online upgrades. This requires that the application in question, as well as any software used by the application (e.g. the database engine) all support online upgrades. Oracle has recognized this problem for years. Unfortunately, up to and including Database 11g Release 1, only a limited number of features have been implemented for that purpose. As of Oracle Database 11g Release 2, this situation has changed greatly. With edition-based redefinition, Oracle Database offers real support for implementing online upgrades. The aim of the paper Edition-Based Redefinition, that I just put online here, is to provide an overview of this new feature.

5 Comments

  1. February 3, 2010    

    How to change Session Edition without downtime (without reconnect to database) ? E.g. a JDBC connection.
    I couldn’t find it after a quick scan of Oracle Documentation.

    • February 4, 2010    

      Hi Charlie

      AFAIK there is no specific API for this. So, you have to execute a regular ALTER SESSION statement. E.g.:

            statement = connection.createStatement();
            statement.execute("ALTER SESSION SET edition = " + edition);

      HTH
      Chris

  2. February 4, 2010    

    Please correct me if I’m wrong. So that means we cannot change other session’s Edition online.
    We either use application to send the “ALTER SESSION SET edition = ” command to every connected session, or use database logon trigger to set Edition and reconnect (restart the application).

    “AFAIK”, learned a new abbr. today. ^_^

    • February 4, 2010    

      Hi Charlie

      The only way to change the session edition is to execute an ALTER SESSION statement or through the SET_EDITION_DEFERRED procedure in the DBMS_SESSION package.

      However, to change the default edition at the database level, it is possible to change the DEFAULT_EDITION database property. It goes without saying that such a change do not impact connected sessions.

      HTH
      Chris

  3. February 5, 2010    

    OK Chris,

    Our deployment procedure will be:

    1) roll in new version PL/SQL package and other database object changes.

    2) change the DEFAULT_EDITION database property.

    3) Application reconnect to database, (restart the connection pool).

    Thanks,
    Charlie

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