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Patching Time

Just a quick note to point out that the October PSU was just released. The database has a few more vulnerabilities than usual (31), but they are mostly related to Java and the high CVSS score of 9 only applies to people running Oracle on windows. (On other operating systems, the highest score is 6.5.)

I did happen to glance at the announcement on the security blog, and I thought this short blurb was worth repeating:

JSON Support in Oracle Database 12c (

I spent a bit of time at OpenWorld looking at the JSON support in Oracle Database 12c. I started to write some stuff about it on the plane home and I spent the last two mornings finishing it off. You can see the results here.

I’ve tried to keep it light, since the documentation does a pretty good job at explaining all the variations of the syntax. I’ve also avoided trying to teach people about JSON itself. There is loads of stuff about that on the net already.

For the most part I think the JSON support looks pretty cool. During the process of writing the articles I did notice a few of things that I thought might confuse.

Temporal Validity, ACLs, External Tables, SQL*Loader and more in Oracle 12c

Some more 12c articles have trickled out over the last few days.

A few more 12c articles

A few more 12c articles went live over the last few days…

The DMU and In-Database Archiving are from the OCP syllabus. The Invisible Columns stuff seemed like a natural thing to mention, when discussing the In-Database Archiving.

The 12c journey continues…




Oracle Database 12c Release 1 ( Patch Released

I just read this post by Dirk Nachbar, saying that is now available from I’ve downloaded it, so the rest of the world is now allowed to start their downloads. :)

I assume it will be available from MOS also at some point.



PS. It will allegedly be made available on OTN at some point in the future.

Invoker Rights in Oracle Database 12c : Some more articles

I wrote about the Code Based Access Control (CBAC) stuff in Oracle Database 12c a while back.

I’ve recently “completed the set” by looking at the INHERIT PRIVILEGES and BEQUEATH CURRENT_USER stuff for PL/SQL code and views respectively.

Automatic Diagnostics Repository (ADR) in Oracle Database 12c

There’s a neat little change to the Automatic Diagnostics Repository (ADR) in Oracle 12c. You can now track DDL operations and some of the messages that would have formerly gone to the alert log and trace files are now written to the debug log. This should thin out some of the crap from the alert log hopefully. Not surprisingly, ADRCI has had a minor tweak so you can report this stuff.

You can see what I wrote about it here:

Of course, the day-to-day usage remains the same, as discussed here:



How Exadata smartscans work

I guess everybody who is working with Oracle databases and has been involved with Oracle Exadata in any way knows about smartscans. It is the smartscan who makes the magic happen of full segment scans with sometimes enormously reduced scan times. The Oracle database does smartscans which something that is referred to as ‘offloading’. This is all general known information.

But how does that work? I assume more people are like me, and are anxious to understand how that exactly works. But the information on smartscans is extremely scarce. Of course there is the Oracle public material, which looks technical, but is little/nothing more than marketing. On My Oracle Support, I can’t find anything on the inner working. Even in the ‘Expert Oracle Exadata’ book (which I still regard as the best source of Exadata related information) there is no material on the mechanics of smartscans.

[Oracle] DB Optimizer Part XI - Query transformation fixes false cardinality estimation with multiple OR predicates (in newer Oracle releases)


This is a short blog post about another query transformation (check my first blog post [Oracle] DB Optimizer Part VIII - Looking under the hood of query transformation (done by CBO) with simple real life example first, if you never heard of the term "query transformations"), that fixes a cardinality estimation issue with multiple (OR) predicates that cover the whole data range. I have to admit that this is a special case, but it can happen as observed by my client

Articles on Oracle Database 12c Multitenant Option

From a technology perspective, the Multitenant option is really cool, but it can be rather difficult to get to grips with some aspects of it. Everything is so intertwined and every feature in 12c somehow links back to the Multitentant option. As I’ve been working my way through the features the same pattern keeps repeating.

  • Write an article on a feature X.
  • Put it live.
  • Move on to looking at feature Y.
  • Notice something about feature Y that affects the article I’ve written about feature X.
  • Go back and revise the article on feature X.
  • Rinse and repeat.

This pattern has made me rather reluctant to post anything on the blog about new articles, because although I don’t release articles until I think they are finished, all these Multitenant articles feel very much like a work-in-progress. I fully expect to step back and revise/rewrite all of them as I figure more out about this stuff.