On April 22-26, 2012 the Independent Oracle Users Group (IOUG) is holding the COLLABORATE 12 forum in Mandalay Bay Convention Center, Las Vegas (US-NV).

The COLLABORATE is a widely known event in the Oracle Community, and attracts lots of Oracle guys and girls from all over the world. I feel honored to contribute a presentation about how to detect and resolve child cursor issues resulting in mutex wait events. It will be Lesson #893 as part of the “Oracle Internals & Performance Bootcamp”, which is maintained by Craig Shallahamer. Here comes the official excerpt from the IOUG session planner:

Thursday, April 26, 2012

#893 – „Resolving child cursor issues resulting in mutex waits“

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Once again this year, the German Oracle Users Group has its annual conference and exhibition in Nuremberg. (DOAG Konferenz und Ausstellung 2011, Nürnberg). Being there is nearly a must for Oracle guys in German speaking countries.

As usual, here comes my unordered, incomplete and ad-hoc list of things I wrote down to have a closer look at in the next year, coming up during or from random talks I attended.

Day 1 (Tue 15.11.2011)

• AVG_ROW_LENGTH of a table vs. Blocksize
• CHAIN_CNT
• analyze table X validate stucture cascade
• Linux: Transcendent Memory
• Linux: CleanCache and zcache
• Linux: Cgroups
• Linux: Transparent Huge Pages (wow!)
• Linux: DTrace
• Linux proprietary: Ksplice
• View: registry$history for the REAL version number
• Rolling Upgradable patches means minimal downtime on on Single Instance DBs, in combination with Out-of-Place-Upgrade)
• Bug 10187168 in PSU 11.2.0.2.2 (_cursor_features_enables=1026
• Typeset conversions: CSscan and DMU utilities
• AIX patch following note 1246995 (Memory Footprint)

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In early April, I had the honour to attend Craig Shallahamer’s Oracle Performance Firefighting and Advanced Performance Analysis courses. It was a great opportunity, since he came to Frankfurt which is just a three hours drive away. It was the second time meeting him – and it was great, again. The last two days have been a bit dry by their theoretical nature, and the last exercises on friday are only of limited use for me. But especially the first three days of firefighting have been really useful and most valuable due to their basic technology insights and the teached strategies “how to be sure”.

Craig Shallahamer in Frankfurt 2011

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For the last three days, I have been in Nuremberg, attending the DOAG Konferenz 2010 (annual conference of the german Oracle user group). This year, my list of “Look at’s” is way shorter than last years list was. It’s not the fault of the event, I just did not write down that many facts.

My general impression was, that the number of talks intersting for DBAs was limited, but all talks I attended have been of high technical quality. Speakers may be more or less gifted, but I am enough of a technican to read behind the presentation to appreciate it.

Here’s my list. Not comprehensive, but this is my basic “lessons to take”:
Day 1:

• Carefully decide how far to rely on RAT (Real Application Testing) feature, it’s not the Golden Bullet.
• Once again, Oracle changed an established name: FRA is now “Fast Recovery Area”
• Use RMAN’s “configure for” command in a dataguard environment
• Use auto-delete for archived redo logs
• Calculate your next migration with Oracle GoldenGate licensing
• Son Of A Preacher Man: stay an IOPS evangelist, if you happen to be a DBA

Day 2:

• Dive deep into SQL*Net / TNS / tcp optimization. Thanks to Dr. Mensah for the enlightenment!
• Oracle now SUPPORTS the RAC on VMware. No certification, but at least something to take home.
• Dear Larry, please make Oracle-at-VMware licensing accept VMware-side CPU assignment, FINALLY!
• Most constraints can have an optimizer upside! Thanks, Mr. Senegacnik!
• 11.2.0.2 has lots of new unexpected features. Unusually. Both in RAC and single instance. Nice!

Day 3:

• Immediately look at the 11.2.0.2 “hang manager”. Thanks, Markus Michalewicz!
• Try a $ORACLE_HOME in ACFS on your next RAC test, looks cute.
• Oracle Clusterware process architecture is confusing, but changes worse in 11.2.0.2, for the first glance. Docs are still a mess, but Dr. Grebe unwired lots of them. Maybe the highlight of my conference 2010!

to be continued…

Best regards
Martin

In January, I’ve bee rather busy, so the blog was left alone. No sense in blogging just to blog.

Now some content. I attended the Oracle Technology Day – Storage Optimisation in Bonn, Germany. It was a nice event, lots of information, a bit commercials, excellent catering. But this is a technical blog, let’s talk abut Oracle technology.

One interesting information was the averages the first speaker, Mr. Gerd Schoen of Oracle, explained. They are mostly valid for OLAP systems, and I don’t claim they are absolutely true, but it was interesting to hear. I neither will comment them, nor discuss them. Just read what I heard.

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Before everyone diappears from The Net(tm) for Christmas:
Have a nice yule-tide, don’t eat too much of the feast, don’t drink and drive, and talk the RDBMS of your choice into operating itself for at least two or three days: You won’t miss the usual 6-in-the-morning phone calls on Christmas!

If you are lucky enough to have real holidays over the next days: A happy new year and let’s work on big red letters in January again! ;)

Yours
Martin Klier

PS: I hope you recognized: The usual omnipresent word starting with an X – it’s missing here. And, it hasn’t been too difficult. :)

Thursday 19th was the last day of DOAG Confernce 2009. Compared with the second day, the program was much more dense: For my (DBA) profile there have been several hours, where more that one talk would have been appropriate.

This list is, what I collected during the day.

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As promised, today my impressions of yesterday (confusing, I know). Clarification: This is about Wednesday, November 18th. I’m still at DOAG Conference 2009 in Nuremberg. Wednesday was a silent day for my interests, especially at noon there have been less talks being of interest, but maybe they have done something for my general knowledge…

So once again, this are impressions, a digital copy of my scratchpad, unordered and without warranty. :)

For SQL Trace analysis:

• let’s look at HOTSOS Profiler by Mr. Milsap, TRCANLZR (Oracle), TV$XTAT, ORASRP and MERTITS Profiler. For the latter, a limited free edition is available (without realtime V$ associations)
• Review the Index usage when date/timestamp datatypes are used
• 11g cursor close type (in a trace file) might enlighten something

Oracle on VM:

• Oracle VM 2.2 uses XEN 3.4 core now
• nice feature of Oracl VM: IO Priority (time slicing)
• Oracle DB in an Oracle VM will have about 10% losses on CPU power
• Oracle VM is limited to 60.000 IOPS :)
• PVM with Direct Driver option is fastest
• Activate Direct IO
• Windows will be faster than on bare metal when running on Oracle VM, due to better IO scheduling

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These days, the DOAG Conference 2009 happens in Nuremberg, Germany. First day was yesterday, Tuesday November 11th 2009. This is a machine-readable copy of my scratchpad, coming from the different talks I attended.

• Sun Oracle Database Machine Exadata 2: The “Quarter Rack” (consisting of 2 Servers and 3 storage nodes) sounds interesting.
• 11gR2 has some features only available with Exadata: For example, a special “Storage Index”, grouping several lines with theit MIN and MAX values in order to minimize scan ranges (called Smart Scan)
• Exadata provides inter-instance IO ressource management possibilities, it might be useful to look at the IO ressource management capabilities of 11g without Exadata as well!
• Really interesting stuff was “Righttime Data Warehousing – reducing latency” of Sven Bosinger; his presentation and the paper will be great material to explain some stuff for conceptional discussions. Thanks, Sven!
• Look at issues for your DB release version! Metalink Note 161818.1 is great for that!!
• Flashback Data Archive may be a good tool for an archiving concept (Oracle sales tells us about Basel II and stuff), but have care!Firstly, DDL on tables prepared for FDA is slow, and secondly and worse, if you have tablespace quotas on your schema, the archiving might stop if it’s full. And that without error messages due to asynchronous archiving. Only way to monitor that is to scan for new trace files all the time. :(
• The new Oracle Grid Infrastructure and its Instance Caging sounds interesting as well. Especially the CPU assignment with CPU_COUNT parameter sound nice, as well as CPU overcommitment (assigning more CPUs than you have).
• Oracle OMotion and RAC One Node are other nice ones: But at the moment, RAC One Node is not available with Standard Edition!

At a glance: The first day was great, and absolutely interesting. Let’s see what Wednesday brings, the program looks promising so far.

Best regards from Nuremberg
Martin Klier

In the last days, My Oracle Support was redesigned. But since flash is a performance eater and not always available, people like to have an option to use My Oracle Support (formerly Metalink) with HTML only.

The link to it is well-hidden, but nevertheless useful!

Give it a try: https://supporthtml.oracle.com

Best regards
Usn