Thursday, October 15, 2009
Tuesday October 13th
Unconference on Indexes
10/13/2009 10:00 AM
I started off the day attending the indexing presentation of fellow Oak Table member Richard Foote. Foote has become quite well known for his expertise on index internals since the publication of Oracle B-Tree Index Internals: Rebuilding the Truth
This was basically a Q&A session, and I will include just a couple of the questions.
Q: Have you ever seen an index Skip Scan used correctly?
A: The short answer was 'No'
Foote mentioned that he had only rarely seen an index skip scan used, and then inappropriately. For more information on skip scan, see Foote's blog entry on Index Skip Scans
Q: When can you safely drop an index that doesn't seem to be used?
A: That is very difficult to determine
The explanation for this answer is that it is very difficult to determine in an index is never used. It does require some patience, as the code that uses the index may be run only rarely, making it difficult to determine if it is actually used
Oracle Closed World
OCW actually started on Monday, though due to the wonders of technology I missed it on that day. The event was invitation only, either by being present when it was mentioned, or by receiving an SMS text on your phone.
This is where technology comes in. The SMS was rather garbled, and I received through a series of very short SMS messages what seemed to be an invitation to stroll into a dark alley somewhere in downtown San Francisco. It was later cleared up and I attended on Tuesday.
Oracle Closed World is the brain child of Mogens Norgaard, another Oak Table member, and co-founder of Miracle AS Oracle consulting
On Tuesday Jonathan Lewis reprised his "How to be an Expert" presentation, the difference being that this audience was comprised of folks with a wide breadth of Oracle knowledge.
Lewis took advantage of this by making the questions harder, and chiding the audience for not knowing the answers. All was in good fun. Undoubtedly the presence of beer didn't make the questions any easier to answer.
Wednesday was a presentation by Jeremiah Wilton, Oak Table member and formerly a DBA at Amazon.com.
Wilton presented a live demo on using Amazon's Elastic Compute Cloud (EC2) to provision a linux server, using Elastic Block Storage (EBS) to provide persistant storage, and preconfigured Amazon Machine Instances (AMI) to build provision the server with Oracle already installed.
The fact that Wilton was able to do this during a 1 hour live demo, complete with the inevitible mishaps that can occur during a live demo, and complete the task was quite impressive.
This appears to be a great method to setup test instances of Oracle for experimentation. There are companies using this for production use as well.
Amazon Web Services
Perl - A DBA's and Developers Best (forgotten) Friend
Arjen Visser - Avisit Solutions
Perl is a topic near and dear to my heart.
I have been using it since version 4 in the early 1990's, and have advocated it's use ever since. It is a robust and powerful language with a huge collection of libraries developed by the user community and archived in the Comprehensive Perl Archive Network (URL HERE: http://cpan.org/)
When I spotted the Perl session on the schedule I immediately signed up for it.
What I had not notice was the subtitle indicating it was a session for beginners.
No matter, I had to go.
The sesssion began with a concise but clear introduction to Perl basics.
So far, so good.
When the time came to discuss Perl connectivity to Oracle, it was a bit surprising to be confronted with a slide showing how to use Perl as a wrapper for sqlplus.
"Surely" I thought, "this is going to be a slide showing how not to do it"
If you have used Perl with Oracle, you are no doubt familiar with DBI and DBD::Oracle
DBI is the Perl Database Interface module developed and maintained by Tim Bunce
DBD::Oracle is the Oracle driver for DBI, also originally developed and mainted by Tim Bunce, and now being maintained by The Pythian Group
DBI and DBD::Oracle are very mature and robust Perl packages for using Perl with Oracle.
You would also likely know that using Perl as a wrapper for sqlplus is something that is very cumbersome and inelegant. So as to not write whole treatise on why you shouldn't do this, I will simply say that doing so is rarely necessary, and never an optimal method.
Which brings us to the next slide in the presentation, which had a diagram showing the how DBI and DBD::Oracle fit into the Perl architecture.
The speaker then told the audience that these were hard to install and difficult to use, and didn't recommend using them.
After picking my jaw back up off the floor, I lost all interest in the rest of the presentation. I don't remember what the rest of the slides were. Maybe I blacked out from the shock. What I remember is walking away from the presentation rather incrudulous.
Just last week, a friend that had not used Perl asked my how to install it on a Solaris server. With only a few lines of email that I typed from memory he was able to successfully install DBI and DBD::Oracle.
Hard to install indeed.
11 Things about 11gR2
Really it was Tom's top 10 list for 11gR2 - he liked his favorite feature so much he counted it twice.
And that is the one I will mention.
It is Edition Based Redefinition,
In a nutshell this feature allows you to create a new namespace for PL/SQL objects, creating new versions in a production database.
This will allow upgrading applications with little or no downtime, something that has always been on of the DBA holy grails.
Rather than try to explain it (OK, I don't yet know know it works) I will just tell you to take a look at Chapter 19 in the 11gR2 Advanced Application Developers Guide.
Ellison promised to discuss 4 topics, I will include 3 of them.
I left before the Fusion Middleware discussion.
Oracle enterprise linux update
One interesting fact presented was a survey performed by HP detailing Linux usage in corporate data centers. The numbers are rather surprising.
* Oracle Enterprise Linux 65%
* Redhat 37%
* Suse 15%
* Other 2%
Next was the second generation of the Exadata Database Machine.
Essentially it is faster then gen 1.
It was used to set a new TPCC benchmark record - I believe it was 1,000,000 transactions per seond.
Ellison was proud of the record being 16 times faster than the record previously set by IBM, and rightfully so if those numbers are correct.
It seems IBM has challenged the results however, claiming the Exadata 2 as 'only 6 times faster'. As you might imagine, Ellison had some fun with that, even offering a $10 million prize to anyone that can show that a Sun Exadata machine cannot run the app at least twice as fast as another other system. IBM is invicted to participate.
At this time Ellison welcomed a special guest to the stage. Californie Governor Arnold Schwarzenegger.
Commenting on being in a room with so many IT folks Schwarzenegger commented "As I came out on stage I felt my IQ shoot up 10 pts."
Schwarzenegger talked for a few minutes on the impact of technology on peoples lives. "Technologies impact is flesh and blood" in reference to how tech is used to aid response of public services such as firefighting.
Arnold called for a round of applause for Larry Ellison and Scott McNeely for being technology leaders.
The camera cut to Ellison, looking uncharacteristically humble as he mouthed 'Thank you'.
After Schwarzenegger left the stage, Ellison continued, this time discussing My Oracle Support.
My Oracle Support has been a hot topic lately, as the majority of DBA's are less than thrilled with the new Flash interface being imposed. It is my understanding that a HTML version of the interface will be maintained, so we won't have to deal with Flash if we don't want to.
Here's where it gets interesting - the unification of Oracle Enterprise Manager and My Oracle Support.
There is now a 'My Oracle Support' tab in OEM.
DBAs will be allowed to opt in to OCM, Oracle Configuration Manager, allowing Oracle to perform automated discovery of bugs and patches needed, either in Oracle or other vendors on server (OS bugs)
Oracle will will then have a global database to mine for proactive response to possible problems.
When a configuration is found to have issues, all users with that configuration can be proactively notified.
The real news IMO though is the impact on patching.
Oracle recently started offering a new patch pacakge - PSU.
This is different than the CPU patch system, as it may require merge patches to resolve patch conflicts.
If OEM My Oracle Support determines that a merge patch is needed, it will automatically file an SR requesting the patch and notify you when it is available.
Even if you don't like OEM, this may be a good use of it.
Ok, that's enough for now, time for lunch.
Posted by Jared at 12:13 PM