Using PDB Relocation to Upgrade an Individual PDB (Doc ID 2771716.1)

Last updated on APRIL 17, 2023

Applies to:

Goal

With the release of Oracle Multitenant, one of the main benefits is the portability of each individual Pluggable Database (PDB).  It is possible to move the self-contained contents of a single PDB from one Container Database (CDB) to another.  In the initial release of Oracle RDBMS 12cR1 this required the PDB to be unplugged from the source CDB and plugged into the destination CDB which could have the potential for extensive downtime.  With 12cR2 the concept of PDB Relocation was introduced, allowing movement of a PDB from one container to another through two SQL commands where the physical copy of the files is performed while the source PDB remains accessible to users and applications.  The final phase of relocation introduces a short downtime of less than 10 minutes to complete the operation The final phase of relocation introduces a short downtime of less than 10 minutes to complete the operation and the upgrade time will vary, generally 30 to 45 minutes based on installed database options and PL/SQL objects, synonyms and used datatypes with complete application downtime typically less than 1 hour. 

The primary use cases for PDB Relocation are from a planned maintenance perspective:

• Performing load balancing by migrating a PDB and its associated resource utilization to a new CDB/host.
• Changing High Availability (HA) tiers for the PDB, such as migrating from a lower service level requirement tier to a higher one.
• Affecting an upgrade of an individual PDB while leaving all existing PDBs at the existing version.

Each of these operations is a physical move of the PDB from one container to another.  There is no reorganization of the PDB or its data as part of this move.

While the low downtime relocate functionality is more directed towards moving PDBs between CDBs of matching patch and version levels, it is also possible to relocate a PDB from a lower to higher version CDB.  Additional downtime is required to perform the upgrade at the destination CDB, but this allows you to upgrade individual PDBs in isolation rather than having to upgrade all PDBs in the CDB at one time.

One of the advantages of Oracle Multitenant is the ability to Manage Many as One and upgrade all PDBs and the CDB together at the same time, saving time and effort.  This document will focus on the exception case where a single PDB is ready to upgrade but other PDBs in the container database are not.

NOTE: During the relocation and upgrade process your applications will experience downtime.  For typical environments you can expect one hour or less, however the downtime is dependent on optional database products installed in the PDB in addition to application PL/SQL code.  It is highly recommended you test this process in a test/dev environment with a representative copy of the PDB to determine what your approximate downtime will be.

This paper will document the process for relocating a pluggable database and upgrading it at the destination, describing:

• Prerequisites for relocate and upgrade
• Preparation steps
• The steps performed during the two phases of relocation.  Application downtime will begin in the second phase of the relocation.
• The steps to perform the upgrade of the PDB
• Post relocation steps

For PDB Relocation where upgrade of the PDB is not required, please see Using PDB Relocation to Move a Single PDB to Another CDB Without Upgrade <Document 2771737.1>.

Solution

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