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May 2018

Some ideas about Oracle Database on Docker

By Franck Pachot

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This is not a ‘best practice’ but just some ideas about building Docker images to provide an Oracle Database. I started with the images provided by Oracle: https://github.com/oracle/docker-images/tree/master/OracleDatabase/SingleInstance and this is great to validate the docker environment. Then I customized for my needs and here are the different points about this customization.

Do not send a huge context at each build attempt

I work by iteration. Sending a 3GB context each time I try a build is a no-go for me. Then I quickly stopped to put the Oracle installation .zip in the context of my build. I already blogged about this.

20 Indexes

If your system had to do a lot of distributed queries there’s a limit on indexes that might affect performance: when deriving an execution plan for a distributed query the optimizer will consider a maximum of twenty indexes on each remote table. if you have any tables with a ridiculous number of indexes (various 3rd party accounting and CRM systems spring to mind) and if you drop and recreate indexes on those tables in the wrong order then execution plans may change for the simple reason that the optimizer is considering a different subset of the available indexes.

18c Scalable Sequences Part III (Too Much Rope)

I previously looked in Part I and Part II how Scalable Sequences officially released in 18c can reduce index contention issues, by automatically assigning a 6 digit prefix to the sequence value based on the instance ID and session ID of the session. We need to be careful and consider this 6 digit prefix if […]

Oracle 18c Security utl_file_dir and schema no authentication

I have managed to build an 18c database this weekend to test and learn on. I have not had a massive time to look into 18c yet but I will do over the coming days and weeks. The new features....[Read More]

Posted by Pete On 07/05/18 At 09:10 PM

FBIs don’t exist

This is a reprint (of a reprint) of a note I wrote more than 11 years ago on my old website. I’ve decided to republish it on the blog simply because one day I’ll probably decide to stop paying for the website given how old all the material is and this article makes an important point about the need (at least some of the time) for accuracy in the words you use to describe things.

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There’s no such thing as a function-based index.

Well, okay, that’s what the manuals call them but it would be so much better if they were called “indexes with virtual columns” – because that’s what they are and that’s a name that would eliminate confusion.

Broadening Your Audience

I spent this week speaking at two conferences that may not be familiar to my usual crowd:
Techwell StarEast Testing Conference in Orlando, FL
Interop ITX Data Conference in Las Vegas, NV

ADWC – the hidden gem: Zepplin Notebook

By Franck Pachot

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In the previous blog posts I explained how to create, and stop/start the Autonomous Data Warehouse Cloud service. And I didn’t show yet how to connect to it. It is easy, from sqlplus or SQL Developer, or SQLcl.

But there’s something more exciting to run some SQL queries: the Oracle Machine Learning Notebooks based on Apache Zepplin. At first, I didn’t realize why the administration menu entry to create users in the ADWC service was named ‘Manage Oracle ML Users’, and didn’t realize that the ‘Autonomous Data Warehouse Cloud’ header was replaced by ‘Machine Learning’.

Free Conference (*) in May!

How do you fancy going to a full-day, five stream conference, for free? With a great agenda including Pete Finnigan talking on the hot topic of GDPR; Chris Saxon, Nigel Bayliss and Grant Ronald giving us the latest low-down on optimizer, 18C database features for developers and AI powered apps? Stalwarts of the Oracle community like Robin Moffat, Zahid Anwar and Andrew Clarke giving their real-world view?

FBI Limitation

A recent question on the ODC (OTN) database forum prompted me to point out that the optimizer doesn’t consider function-based indexes on remote tables in distributed joins. I then spent 20 minutes trying to find the blog note where I had demonstrated this effect, or an entry in the manuals reporting the limitation – but I couldn’t find anything, so I’ve written a quick demo which I’ve run on 12.2.0.1 to show the effect. First, the SQL to create a couple of tables and a couple of indexes:

StarEast, InteropITX and GDPR

I’m getting ready to get on a plane between two events today and have been so busy, that there’s been a break in blogging.  That’s right folks, Kellyn has let a few things slide….