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August 2012

Debugging

One of my recent assignments involved a company that had run into some performance problems after upgrading from 10.2.0.3 to 11.2.0.2. We had spent half an hour on the phone discussing the system before I had arrived, and I’d made a couple of suggestions that had solved most of their problems before I got on site – but they still wanted me to come in and give them some specific ideas about why the critical part of the solution had helped.

The most critical piece of advice I had given them (after listening very carefully to their description of the system) was to get rid of ALL the histograms they had on their system, and then watch very carefully for any signs that they might need to re-introduce a handful of histograms over the next few weeks.

What I learned new about Total Recall...

Today I learned something new about the Oracle Total Recall option from a good friend (they were very happy to have told me something about Oracle I didn't know :) ) - it doesn't exist anymore!  The Total Recall option has been made part of the Advanced Compression option!!

Check this out http://docs.oracle.com/cd/E11882_01/license.112/e10594/options.htm#CJACCDBA to see what you get with the Advanced Compression option which now includes the Total Recall option as well - the Flashback Data Archive capability.
:)))))))))))

Lessons From Rural Africa

It has been nine months since I’ve written here. Needless to say, a lot has happened!

First, my family was living in Africa for three months earlier this year while I did some tech work at an NGO hospital. Second, upon our return I decided to join the good people at Pythian. I’m not moving to Canada, although I will travel a decent bit as part of the company’s consulting group.

If you’re interested in the Africa trip, look at the Africa page. I wasn’t working with Oracle technology but it was still a very interesting, challenging and engaging project.

I thought I’d briefly share a few high-level insights. You might be surprised how well these lessons apply almost anywhere (even Oracle-related projects)!

Four Lessons from IT in Rural Africa

  1. Understand the Fundamentals

Lessons From Rural Africa

It has been nine months since I’ve written here. Needless to say, a lot has happened!

First, my family was living in Africa for three months earlier this year while I did some tech work at an NGO hospital. Second, upon our return I decided to join the good people at Pythian. I’m not moving to Canada, although I will travel a decent bit as part of the company’s consulting group.

If you’re interested in the Africa trip, look at the Africa page. I wasn’t working with Oracle technology but it was still a very interesting, challenging and engaging project.

I thought I’d briefly share a few high-level insights. You might be surprised how well these lessons apply almost anywhere (even Oracle-related projects)!

Four Lessons from IT in Rural Africa

  1. Understand the Fundamentals

Compression Units – 4

Following up a suggestion from Kerry Osborne that I show how I arrived at the observation I made in an earlier posting about the size of a compression unit, here’s a short note to show you what I did. It really isn’t rocket science (that’s just a quick nod to NASA and Curiosity – the latest Mars rover).

Step 1: you can access rows by rowid in Oracle, so what happens when you try to analyze rowids on Exadata for a table using HCC ? I created a table with the option “compress for archive high” and then ran the following query:

Latin America OTN Tour....

Just starting the Latin American OTN tour for the week here in Uruguay.

This is my first time in Uruguay and I spent the weekend in Montevideo.  It was a wet, damp weekend - very foggy too!  But on the plus side - the food is excellent and plentiful.  The local user group leaders here made sure we were well fed and warm for lunch every day :)

Today is the OTN conference - Dimitri Gielis is presenting right now using a "slide free" presentation.  He is building an APEX application to the specification of the audience, in real time.  A pretty neat concept, I like it, very good way to show the ability of the tool:

2012-08-06_14-57-22_202

Arithmetic

Here’s an amusing little question that appeared on OTN a short while ago:

From the performance point of view, which of the following is better and why :

(1) select FILE_NAME, TABLESPACE_NAME, SUM(BYTES)/1024/1024/1024 from dba_data_files

(2)  select FILE_NAME, TABLESPACE_NAME, SUM(BYTES)/(1024*1024*1024) from dba_data_files

Assuming we add the necessary “group by” clause to the end of the queries, how could we find out if there is any difference (other than testing the queries on a system with a very large number of data files to see if we can spot a difference in the CPU usage caused the by change in the arithmetic expression ?

Webinar Material

Thanks everyone who attended my last webinar at AllThingsOracle.com.

The recording of the webinar and all scripts used during the live demos are now available for download.

The README.TXT contains a description of the scripts used - there are a couple of helper scripts along with the main scripts, so that should allow you understanding which scripts you need to use for reproducing the issues demonstrated.

Furthermore the README contains links to some of the resources on the Internet that address questions that were raised during the Q+A session.

Thanks again to AllThingsOracle.com and James Murtagh for hosting the event.

Getting good at stuff…

Last night was a fantastic night for UK athletics. I have to admit I felt rather emotional during the medal ceremony for Jessica Ennis…

I really hope the message viewers (especially kids) take away from these events is that to get good at anything you’ve really got to work at it. In these days of instant fame on reality TV shows, it seems the world has forgotten that it takes time and effort to get good at stuff. It’s easy to brush this stuff off by saying, “they’ve got great genetics”, or, “they have natural ability”, but when Mo Farrah talks about doing 125 miles per week in training, you start to understand this isn’t just natural ability…

What’s this got to do with IT and Oracle?