Oracle Database 12c review: Finally, a true cloud database
Pluggable databases bring a new level of efficiency and ease to database consolidation, while a wealth of other new features address performance, availability, and more
You can also perform cross-platform backups and restores in Database 12c without needing to explicitly convert endianness. If only Oracle could also supply a method to convert endianness of archive log files, because it would greatly simplify migrations between platforms with different endianness. Without the ability to convert the endianness of archive log files, we must resort to replication products, such as Golden Gate, to reduce the database downtime during platform migration.
In addition to the major improvements outlined above, Database 12c introduces many relatively minor enhancements that will be important to DBAs. Here are a few of the most noteworthy.
Materialized View Refresh. Non-atomic refreshes of a materialized view can affect the performance of user queries due to the need to maintain read consistency. Delete statements are used for non-atomic refreshes, so if another SQL query accesses the materialized view concurrently, then the query will suffer from performance issues because the query must apply enormous amount of undo records to reconstruct read consistent blocks. Version 12c introduces new optimization, so instead of deleting from original table, a new identical table is populated with refreshed data. At the completion of refresh, tables are swapped, thus completing the out-of-place refresh. Users can query the original table without incurring any additional overhead. This strategy provides operational convenience to refresh materialized view with minimal impact.
IPv6 support. Many organizations are gearing up to certify IPv6 support as IPv4 address space becomes exhausted. Database 12c supports IPv6 for public network addresses. It does not support IPv6 in private network addresses, but this is probably a non-issue.
Parallel upgrade. This is a feature I have been looking for over many years. In highly available environments, keeping the database down for a database upgrade, even for a few hours, is cost-prohibitive. Rolling upgrades are not always possible for major database software upgrades, and it is always a risky adventure to tune Database Upgrade itself. Version 12c uses parallelism to improve the database upgrade to reduce upgrade-related downtime.
Password files in ASM. Another important Database 12c feature is the ability to store password files in ASM (Automatic Storage Management). In RAC, changing passwords for privileged users is a cumbersome task. Even with the use of NFS or another shared file system for the password file, grants must be executed in all instances. In Database 12c, password files are stored in ASM -- and grants need to be executed in just one instance.
The wealth of new features in Oracle Database 12c gives Oracle shops many reasons to consider upgrading. If you manage a cloud database, or wish to improve resource utilization by consolidating multiple databases on shared hardware, you should consider upgrading sooner rather than later. The new pluggable databases feature is extremely useful for co-locating multiple applications in a single database instance.
If you frequently clone databases over a WAN, then you should consider upgrading to to take advantage of RMAN's native compression when transferring the files. If your employer mandates IPv6 protocol support, then you should look at upgrading. Further, sites that make use of numerous materialized views can benefit from the new refresh methods available in the new version.
Finally, if you are currently in the process of designing or developing an application with high-availability focus, then you should take a close look at the Transaction Guard and Application Continuity features introduced in 12c.
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