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November 2018

Log in to Ubuntu VMs in Oracle Cloud Infrastructure

When I learned that Oracle was providing Ubuntu images in Oracle Cloud Infrastructure (OCI) I was a bit surprised at first. After all, Oracle provides a great Enterprise Linux distribution in the form of Oracle Linux. As a Ubuntu fan I do of course appreciate the addition of Ubuntu to the list of supported distributions. In fact it doesn’t end there, have a look at the complete list of Oracle provided images to see what’s available.

Trying Ubuntu LTS

I wanted to give Ubuntu a spin on OCI and decided to start a small VM using the 16.04 LTS image. I have been using this release quite heavily in the past and have yet to make the transition to 18.04. Starting the 16.04 VM up was easily done using my terraform script. Immediately after the terraform prompt returned I faced a slight issue: I couldn’t log in:

Shrink Space

I have never been keen on the option to “shrink space” for a table because of the negative impact it can have on performance.

I don’t seem to have written about it in the blog but I think there’s something in one of my books pointing out that the command moves data from the “end” of the table (high extent ids) to the “start” of the table (low extent ids) by scanning the table backwards to find data that can be moved and scanning forwards to find space to put it. This strategy can have the effect of increasing the scattering of the data that you’re interested in querying if most of your queries are about “recent” data, and you have a pattern of slowing deleting aging data. (You may end up doing a range scan through a couple of hundred table blocks for data at the start of the table that was once packed into a few blocks near the end of the table.)

Data Warehouse Design: To Index, or Not to Index, that is the question

This post is part of a series that discusses some common issues in data warehouses.

When you query a star schema, you essentially have two choices;

  • bitmap index and star transformation 
  • full scan, bloom filter, and hash join

Star Transformation 

Star transformation was introduced in Oracle 8(see also Oracle Optimizer Blog: Optimizer Transformations: Star Transformation).   A star transformation requires:

IRR function in PLSQL

We had an AskTOM question recently about how to calculate the IRR, ie, the Internal Rate of Return. To be honest, I had not really heard of the function, but readers were quick to point out to me that it was a commonly used function in the most “popular” database on earth, namely Microsoft Excel Smile

Bait and Switch

Just what you need after a long hike in the Lake District:

You need 10 minutes! Not 5, not 15, not 7

What follow is just my opinion….Well duh, it’s a blog, of course it’s just my opinion, but I’ll try back up my rantings and pontificating with some reasoned arguments. Whether at the end of it, you still call my claims total BS is of course entirely within your rights and your opinion </p />
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Terraforming the Oracle Cloud: choosing and using an image family

For a few times now I have presented about “cloud deployments done the cloud way”, sharing lessons learned in the changing world I find myself in. It’s a lot of fun and so far I have been far too busy to blog about things I learned by trial and error. Working with Terraform turned out to be a very good source for blog posts, I’ll put a few of these up in the hope of saving you a few minutes.

This blog post is all about creating Ubuntu images in Oracle Cloud Infrastructure (OCI) using terraform. The technique is equally applicable for other Linux image types though. In case you find this post later using a search engine, here is some version information that might put everything into context:

#DOAG2018 Impressions

As every year in November, the database circus moved to Nuremberg on behalf of the annual DOAG conference. As you may know, this conference has very high standards in terms of turnout and top-notch speakers and it reached them once again: It was a great event!

It started with the welcome keynote where Stefan Kinnen told us that the conference attracted over 2000 attendees and more than 400 speakers from all over the world. That should make it the largest database conference in Europe, I suppose!

Happy Thanksgiving!

Just a quick blog post from Wellington New Zealand where we have just wrapped up the 2018 APAC Groundbreakers tour. It was a great way to finish the event with a small but enthusiastic crowd here in New Zealand.

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AUSOUG “Oracle Master” Award

  I was very flattered and honoured to be named one of the first 4 “Oracle Masters” by the Australian Oracle User Group at the recent AUSOUG Connect 2018 conference in Melbourne. Thank you to all the AUSOUG members involved for this award. As always, it’s a pleasure to help fellow Oracle Database professionals in […]