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Home » Monthly archive

October 2011

Returning to the Day Job.

Submitted by mwidlake on Tue, 2011-10-18 09:10

Having the Summer off. It’s something that quite a few IT contractors and some consultants say they intend to do…one year. It’s incredibly appealing of course, to take time off from your usual work to do some other things. Asking around, though, it is not something many of us self-employed types who theoretically could do, actually have done. I think it is because, although the theory is nice, the reality is a period not earning a living – and the background worry of “if I take a break, will I be able to step straight back into gainful employment afterwards”?

AIOUG Webcast: Methodical Performance Tuning

Submitted by arupnanda on Tue, 2011-10-18 06:00

A big thank you to all those you attended my session today. I sincerely hope you got something out of it. Here are the scripts I used in the demo. And, here is the slide deck, if you are interested.

Remember, this was just the beginner's session. We will have intermediate and advanced ones in near future. Stay tuned through the AIOUG site.

Counting Triangles Faster

Submitted by Greg Rahn on Mon, 2011-10-17 22:05

A few weeks back one of the Vertica developers put up a blog post on counting triangles in an undirected graph with reciprocal edges. The author was comparing the size of the data and the elapsed times to run this calculation on Hadoop and Vertica and put up the work on github and encouraged others: “do try this at home.” So I did.

Compression

Vertica draws attention to the fact that their compression brought the size of the 86,220,856 tuples down to 560MB in size, from a flat file size of 1,263,234,543 bytes resulting in around a 2.25X compression ratio. My first task was to load the data and see how Oracle’s Hybrid Columnar Compression would compare. Below is a graph of the sizes.

Volatile Data, Dynamic Sampling And Shared Cursors

Submitted by randolf.geist on Mon, 2011-10-17 19:39

For the next couple of weeks I'll be picking up various random notes I've made during the sessions that I've attended at OOW. This particular topic was also a problem discussed recently at one of my clients, so it's certainly worth to be published here.

In one of the optimizer related sessions it was mentioned that for highly volatile data - for example often found in Global Temporary Tables (GTT) - it's recommended to use Dynamic Sampling rather than attempting to gather statistics. In particular for GTTs gathering statistics is problematic because the statistics are used globally and shared across all sessions. But GTTs could have a completely different data volume and distribution per session so sharing the statistics doesn't make sense in such scenarios.

So using Dynamic Sampling sounds like a reasonable advice and it probably is in many such cases.

Move the EM12c repository database

Submitted by martin.bach on Mon, 2011-10-17 15:55

I have made a little mistake creating a RAC database for the OEM 12c repository-I now need a little more lightweight solution, especially since I’m going to do some fancy failover testing with this cluster soon! An 11.2.0.3 single instance database without ASM, that’s what I’ll have!

Now how to move the repository database? I have to admit I haven’t done this before, so the plan I came up with is:

  1. Shut down the OMS
  2. Create a backup of the database
  3. Transfer the backup to the destination host
  4. Restore database
  5. Update OEM configuration
  6. Start OMS

Sounds simple enough, and it actually was! To add a little fun to it I decided to the use a NFS volume to backup to. My new database host is called oem12db, and it’s running Oracle 11.2.0.3 64bit on Oracle Linux 6.1 with UEK. I created the NFS export using the following entry in /etc/exports:

Real Steel…

Submitted by oraclebase on Mon, 2011-10-17 13:36

If you remove the humans from Real Steel, you pretty much have Rocky.

As far as the humans are concerned, Hugh Jackman is ok. The kid who plays his son is a little annoying, but to be fair, so are most of the kids in films. There are quite a few cheesy moments, but they are spread out so they aren’t like fingernails down a chalkboard.

I think the biggest problem with the film is the robots have no personalities. It’s just a giant and very expensive version of Rock’em Sock’em Robots. It’s hard to engage with a chunk of metal when it has no outward signs of personality. They are nothing like Transformers, which are totally real. :)

Having said that, its an OK bit of mindless fun. I tried to listen to other people talking on the way out to gauge the general reaction. It seemed to vary from “Awesome!” to “What a complete pile of xxxx!”. I guess I stand somewhere in the middle.

Cheers

Tim…




OOW2011 A.P. (After Presentation)

Submitted by doug on Sun, 2011-10-16 22:12

Wednesday

OEM 12c , cloud control

Submitted by khailey on Fri, 2011-10-14 20:28

Was emailing with my esteemed college John Beresniewicz at Oracle in the OEM group. John and I worked together on OEM 10g and thank goodness he is still there as he is generally behind any good quantitative visualizations you might see in the product. Here is one cool example he sent me:

The database load, AAS, can be time selected and from the selection a load map is shown, in this case of which objects are creating the most I/O load, group by type of I/O. Super cool. Congrats JB and I look forward to exploring more in OEM 12c “cloud control”.

 

 

Friday Philosophy – The One Absolute Requirement for System Success

Submitted by mwidlake on Fri, 2011-10-14 14:16

Alternative title “The lady from Patient Admin – she says YEEESSSS!!!!!!”

What must you always achieve for an IT system to be a success?

  • Bug free? Never happens.
  • Within budget/time frame? That would be nice.
  • Includes critical business functionality? Please define critical.
  • Secure? Well, it’s important for many systems but then it is often lacking (even when it is important).
  • That it is to specification? Well we all know that’s wrong.

There is only one thing that an IT system must always achieve to be a success.

User Acceptance.

For an individual system other considerations may well be very important, but the user acceptance is, I think, non-negotiable.

A History of (my) Certifications…

Submitted by oraclebase on Fri, 2011-10-14 10:54

I was chatting with the lady doing OCP Lounge registrations at OOW11. During this chat I mentioned I hadn’t received a certificate for the SQL Expert certification. It never crossed my mind to re-request it, since my certifications are visible on certview.oracle.com anyway. Yesterday, a DHL man delivered the missing certificate, which prompted me to look though my certifications and scan this image.

First, check out the card on the bottom right. I was unaware the “Expert” certifications had a different colour card.

Second, notice anything funny about the 9i DBA OCP certification?

It’s hard to believe it’s over 12 years since I first completed one of these certifications… :)

Cheers

Tim…