Oracle 11g/12c to 19c Migration Guide

Oracle Database 11g is no longer supported, and the end of support for version 12c is fast approaching. Now is the time to consider migrating to Oracle Database 19c, which offers numerous new features. However, several points require careful attention, and different migration methods are available. Let us take a closer look.

On June 16, Oracle updated the release roadmap for its Oracle Database software.

Support for version 11.2.0.4 will end on December 31, 2020. Oracle offers its customers two additional years of paid assistance through its ACS (Advanced Customer Services) offering to help them migrate these databases. This service includes Level 1 bug fixes, security bug fixes, update planning and access to a Technical Account Manager.

The selected version should be a “Long-Term Release”, meaning a version with the longest possible support period.

In this document, Oracle distinguishes between two types of release:

• “Innovation Releases”, which have a shorter support period, such as versions 12.2.0.1 and 18c;
• “Long-Term Releases”, such as version 19c, which will be supported at no additional cost until April 2024, with the option of purchasing three additional years of extended support.

As a reminder, Oracle changed its version naming convention by naming releases according to their year of release. However, version 18c is actually version 12.2.0.2, while version 19c is version 12.2.0.3. This is important when assessing application compatibility.

New features and benefits of Oracle Database 19c

Version 19c will be the final Oracle Database release to support the creation of non-container databases. From version 20c onwards, all Oracle databases will therefore use the container model.

This container model, known as Multitenant, makes it possible to consolidate several databases into a single database while retaining individual granularity in terms of security, backup and other operations. Since version 19.3, it has been possible to use up to three Pluggable Databases without purchasing the paid Multitenant option.

Like every new release, Oracle Database 19c introduces a wide range of new features:

• Redirection of DML operations to a standby database with Active Data Guard;
• Automatic flashback of the standby database when the primary database is flashed back;
• Automatic indexing for databases hosted in Oracle Cloud or on Exadata;
• Real-time statistics;
• Hybrid partitioned tables, with some data stored in the database and some in flat files;
• Database duplication using DBCA in silent mode and relocation of a PDB to another CDB using DBCA;
• Installation of the Oracle client from an image;
• SQL statement quarantine;
• Privilege usage analysis;
• And more.

The complete list of new features is available in the Oracle documentation.

Oracle Database 19c in container mode is currently the best option for migrating from versions 11g, 12c Release 1 or 12c Release 2.

Migrating to Oracle Database 19c: key considerations

A database migration is always a stressful process, both for DBAs and for application users. It is advisable to carry out the migration on a like-for-like basis and then, once the application has been stabilised, begin implementing selected new features.

The main risks include:

• Loss or alteration of information, particularly when changing character sets;
• Application queries being processed differently due to changes in the Oracle Optimizer, potentially resulting in inefficient execution plans or incorrect results;
• Applications using features that are no longer supported by Oracle, such as the UTL_FILE_DIR, 07_DICTIONARY_ACCESS and STANDBY_ARCHIVE_DEST parameters, Oracle Warehouse Builder—which can no longer be installed using the installation wizard—Oracle Multimedia, Oracle Streams, RAC in Standard Edition 2, Oracle Advanced Replication, certain XML DB features and Enterprise Manager Database Control;
• The need to perform a compliance assessment using the Oracle documentation.

Extensive testing will therefore be required to ensure that the application works correctly before the production databases are migrated. Oracle provides a tool called Real Application Testing, which can capture activity from a production database and replay it in the new version to validate its behaviour.

It is also possible to migrate the current database both to a newer version and to a new hosting environment by using an Oracle Cloud database. To support this process, Oracle provides a tool called ZDM (Zero Downtime Migration), which makes it possible to move a database to Oracle Cloud with only a very short service interruption.

Databases in Oracle Cloud may be self-managed services running version 19c, such as Autonomous Data Warehouse or Autonomous Transaction Processing, or databases running versions 11g, 12c, 18c or 19c and hosted on a Bare Metal or virtualised cloud service. Once created in Oracle Cloud, the database can be migrated in the same way as a database hosted on the customer’s premises.

Different migration methods for Oracle Database 19c

Several methods can be used to migrate to Oracle Database 19c. We have selected three of the most commonly used approaches.

A direct upgrade is a straightforward solution. It can be carried out using Database Upgrade Assistant (DBUA), AutoUpgrade—see Mike Dietrich’s blog—or manually. However, the operating system must be compatible with both database versions. For example, Oracle Database 11g can be installed on Red Hat Enterprise Linux 5 and 6, whereas Oracle Database 19c can only be installed on Red Hat Enterprise Linux 7 and 8. Furthermore, depending on the source version, a direct upgrade is not always possible.

An upgrade combined with a migration can be performed using four different solutions, depending on the source database version and any related changes. Each solution offers a different level of complexity and speed:

• Method 1: DBUA or an upgrade using command-line utilities;
• Method 2: Full database transport or transport by tablespace;
• Method 3: Data export and import.

Get expert support for a stress-free migration

To keep your databases secure, now is the time to consider migrating to Oracle Database 19c. This will give you access to a supported, more secure and more efficient technology platform offering a wide range of new features.

We can support you by carrying out a preliminary assessment to analyse the compatibility of your current system with a more recent version of Oracle Database, verify compliance with Oracle’s rules, test application functionality and complete the migration either on premises or in the cloud.

We can also maintain your databases in operational condition, with strong service-level commitments providing up to 99.9% availability, 24/7.

Need an expert?

For further information or support with the deployment or migration of your environments, please contact us.