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October 2011

Why Is My Index Not Being Used No. 2 Solution (The Narrow Way)

As many have identified, the first thing to point out is that the two queries are not exactly equivalent. The BETWEEN clause is equivalent to a ‘>= and <=’ predicate, whereas the original query only had a ‘> and <’ predicate. The additional equal conditions at each end is significant. The selectivity of the original query is basically costed [...]

Adding another node for RAC on Oracle Linux 6.1 with kernel-UEK

As I have hinted at during my last post about installing Oracle on Oracle Linux 6.1 with Kernel UEK, I have planned another article about adding a node to a cluster.

I deliberately started the installation of my RAC system with only one node to allow my moderately spec’d hardware to deal with a second cluster node. In previous versions of Oracle there was a problem with node additions: the $GRID_HOME/oui/bin/ script did pre-requisite checks that used to fail when you had used ASMLib. Unfortuntely, due to my setup I couldn’t test if that was solved (I didn’t use ASMLib).


Book Review: Oracle Database 11g Performance Tuning Recipes (Part 2)

October 6, 2011 Hammering a Square Peg into a Round Hole: Fine Edges are Lost, Gaps in Detail (Back to the Previous Post in the Series) In an effort for my review to be fair, I have completed the review for the second half of the “Oracle Database 11g Performance Tuning Recipes” book (omitting the pages for chapters [...]

Rise of the Machines

This is the penultimate day of #OOW11 and I am here at the hotel lobby trying to put some order around the myriads of nuggets of information I have had over the last several days.

The announcements this year have been centered around introduction of various new products from Oracle - Oracle Database Cloud, Cloud Control, Database Appliance, Big Data Appliance, Exalytics, T4 Super cluster and so on. One interesting pattern that emerges from the announcements that is different  from all the previous years is the introduction of several engineered and assembled systems that perform some type of task - specialized or generic. In the past Oracle announced machines too; but not so many at the same time, leading to an observation by April Sims (Executive Editor, Select Journal) that this year can be summed up in one phrase - Rise of the Machines.

Runstats utility

A variation on Tom Kyte's invaluable RUNSTATS utility that compares the resource consumption of two alternative units of work. Designed to work under constrained developer environments and builds on the original with enhancements such as "pause and resume" functionality, time model statistics and the option to report on specific statistics. ***Update*** Now available in two formats: 1) as a PL/SQL package and 2) as a free-standing SQL*Plus script (i.e. no installation/database objects needed). January 2007 (updated October 2011)

Mystats utility

A variation on Jonathan Lewis's SNAP_MY_STATS package to report the resource consumption of a unit of work between two snapshots. Designed to work under constrained developer environments, this version has enhancements such as time model statistics and the option to report on specific statistics. ***Update*** Now available in two formats: 1) as a PL/SQL package and 2) as a free-standing SQL*Plus script (i.e. no installation/database objects needed). June 2007 (updated October 2011)

OOW11: Monday and Tuesday…

Monday: I went to some presentations, hung around in the OTN lounge and ate at every possible opportunity. Tanel Poder‘s presentation on “Large-Scale Consolidation onto Oracle Exadata: Planning, Execution, and Validation” was pretty cool.

In the evening I planned to meet a former colleague at the OTN party. I decided they best way to find him was to visit every food station at the party, which of course meant sampling the goods. Unfortunately I spent too much time eating and not enough time looking for him. Sorry Ian! The cool thing about Open World is you can enter a giant tent full of thousands of people and pretty much guarantee you will bump into loads of people you know. :)

Tuesday: I spent most of Tuesday helping out at RAC Attack in the OTN Lounge. I did manage to get to see Greg Rahn‘s presentation called “Real-World Performance: How Oracle Does It”, which focussed on Real-Time SQL Monitoring. Greg’s presentation style is really easy to listen to and you know this isn’t just theoretical knowledge. He’s in the trenches doing this stuff as part of the Real-World Performance Group.

As the afternoon progressed I felt a little tired, so I went back to the hotel, puked and fell asleep. I think this was more to do with being over-tired than anything else. That meant I missed some of the later sessions and didn’t hook up with anyone in the evening.

This morning I feel a little ropey, but I’m going to head on down to RAC Attack again and see if I can make myself useful. Tonight is the appreciation event, but I’m not sure if I will be able to “appreciate it” unless I get a major energy injection at some point today. :)



Oracle Database 11gR2 on OL6 / RHEL6: Certified or Not?

There seems to be a little confusion out there about the certification status of Oracle Database 11gR2, especially with the release of the patchset which fixes all the issues associated with RAC installs on OL/RHEL 6.1.

Currently, 11gR2 is *NOT* certified on OL6 or RHEL6. How do I know? My Oracle Support says so! Check for yourself like this:

  • Log on the My Oracle Support (
  • Click the “Certifications” link.
  • Type in the product name, like “Oracle Database”
  • Select the product version number, like “″.
  • Select the platform, like “Linux x86_64″ or a specific distro beneath this.
  • Click the “Search” button.

From the results you will see that Oracle Database is certified on OL and RHEL 5.x. Oracle do not differentiate between different respins of the major version. You will also notice that it is not currently supported on OL6 or RHEL6.

Having said that, we can expect this certification really soon. Why? Because Red Hat has submitted all the certification information to Oracle and (based on previous certifications) expects it to happen some time in Q4 this year, which is any time between now and the end of the year.

With a bit of luck, by the time I submit this post MOS certification will get updated and I will happily be out of date… :)



HCC – 2

Just a little follow-up to my previous note on hybrid columnar compression. The following is the critical selection of code I extracted from the trace file after tracing a run of the advisor code against a table with 1,000,000 rows in it:

My Presentation "Getting the Best from the Cost Based Optimizer" at Oracle Open World 2011

Today (Tuesday, October 4th 2011) I had my presentation at OOW 2011 in Hotel InterContinental at 13:15 titled "Getting the Best from the Cost Based Optimizer". The room was already sold out on Thursday and I really expected to have a full room - cca 270 people. The room was too small for all who want attending the presentation. Although there were no seats available quite a lot of them were standing in the back.

This time my presentation was not very technical one (in my eyes). I just wanted to point out problems I see many times in real life when people don't really know about some features or behavior of the CBO. Unfortunately one hour was not enough to explain in details why things are going wrong and also show all relevant details. But as I said, the aim was to point out the problems and also give directions what one has to do to get rid of them and according to the reactions of the audience after the presentation the goal was achieved.