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18c

TKPROF’s Argument PDBTRACE

If you run TKPROF without arguments, you get a complete list of its arguments with a short description for each of them (here the output generated by version 18.1.0):

Oracle Database 18c: Introduction to Memoptimized RowStore (Memory of a Free Festival)

One of the potentially cool new features introduced in Oracle Database 18c is the Memoptimized RowStore, designed to improve the performance and scalability of key-value based queries. A new pool in the SGA called the Memoptimize Pool can be configured to store specific heap tables that you may wish to optimize, in a manner not […]

Scripts to Download Oracle Database 18c Documentation

In the past I already shared with you the scripts I use to download the Oracle Database documentation. The aim of this short post is to reference the scripts I just wrote for 18c.

Happy downloading as well as happy reading!

PS: I also refreshed the scripts for 12.1 and 12.2.

18c merge partition online

One of the cool things in 18c is the ability to merge partitions without causing a service interruption.  Here’s a video demonstration of that in action:

This is just an accompanying blog post to let you grab the scripts for the demo so that you can try this yourself on livesql.oracle.com, or any of the Oracle Cloud services that will be running 18c in the near future.

18c–If you can’t wait

You’ve seen the tweet !!

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but perhaps the accompanying blog post has tempered your enthusiasm Sad smile

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You might be thinking:

Oracle Database 18c

Yup…it’s arrived!

New name obviously, because we’ve jumped to our new naming model to align with the calendar year as opposed to version number.  You might be thinking “So what?” but it’s a significant change in the way we getting software to customer.  Mike Dietrich blogged about this at length here so I won’t repeat what has been said, but in TL;DR form:

More frequent releases, with smaller amounts of change per release

In this way, the approach lets us focus more of solidifying existing features, and being able to quickly respond to bugs that arise.

So 18c is more an incremental release on 12.2 (in fact, internally it was referred to as “12.2.0.2” for most of it’s build cycle) focussed on stability and hardening of existing features.

Activating and Deactivating Performance Feedback

Performance feedback is one of the adaptive query optimizer features introduced in Oracle Database 12c. The aim of this short post isn’t to explain how it works, but to simply warn you about a buggy behavior in its configuration.

The parameters that control performance feedback in 12c are the following:

  • OPTIMIZER_ADAPTIVE_FEATURES (12.1 only): if set to TRUE (default), performance feedback is enabled. Otherwise, it is disabled.
  • OPTIMIZER_ADAPTIVE_STATISTICS (12.1 with patch 22652097, and 12.2): if set to TRUE, performance feedback is enabled. Otherwise, which is the default, it is disabled.
  • PARALLEL_DEGREE_POLICY (12.1 and 12.2): it has to be set to ADAPTIVE (default is MANUAL) to enable performance feedback.

So far, so good.