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September 2019

UKOUG 2019

At the UKOUG TechFest 2019 event in Brighton this year I’ll be chairing the CBO Panel session on Monday 2nd December at noon. The panellists will be Maria Colgan, Nigel Bayliss, Christian Antognini and Richard Foote.

It will be possible to propose questions on the day – written or spoken, but this if you have a question that you’d like to give the panellists a little warning about then you can:

Installing an #Exasol 2+0 Cluster on Hyper-V

After having installed Hyper-V, an ISO file with the Exasol software needs to be downloaded. The 2+0 cluster consisting of two data nodes and one license server needs a host machine with at least 8 GB memory and 60 GB free disk space. I do it on my Windows 10 notebook with 16 GB memory. This is for educational purposes of course and not suitable for production use.

2+0 means two active nodes and no reserve node. A reserve node can be added later, expanding the environment to a 2+1 cluster.

We’ll start adding two virtual switches to be able to connect the network adapter of the VMs to them later.

Create Hyper-V Switches for Private and Public Network of the cluster

Click the Virtual Switch Manager in Hyper-V Manager:

Presenting at UKOUG Techfest19 Conference in Brighton, UK

I’m very excited to be attending my 3rd UKOUG Conference, this year re-badged as Techfest19. The fact it’s being held in Brighton is a little disconcerting for a Crystal Palace fan, but really looking forward nonetheless to what has always been one of the very best Oracle conferences on the yearly calendar. I have a […]

19c High-Frequency statistics gathering and Real-Time Statistics

Those are the two exciting new features about the optimizer statistics which arrived in the latest release of 12cR2: 19c. Less exciting is that we are not allowed to use them in any other platform than Exadata:

https://apex.oracle.com/database-features/

But let’s cross the fingers and hope that this will be released in the future because they solve real-life problems such as Out-of-Range queries. Here is a little example involving both of them. A table starts empty and is growing during the day. Relying only on the statistics gathered during the maintenance window will give bad estimations. And dynamic sampling may not sample the right blocks.

Announcement: Australia/NZ “Let’s Talk Database” Events October 2019 !!

I’ve very excited to announce the next series of Oracle “Let’s Talk Database” events to be run throughout Australia and New Zealand in October 2019. I’ll be discussing two exciting topics this series, “Oracle Database 19c New Features” and “Oracle Exadata X8“. As always, these sessions run between 9am-1pm, include a networking lunch and are free, […]

Oracle Database 19c Automatic Indexing: Default Index Column Order Part II (Future Legend)

In Part I, we explored some options that Oracle might adopt when ordering the columns within an Automatic Index by default, in the absence of other factors where there is only the one SQL statement to be concerned with. A point worth making is that if all columns of an index are specified within SQL […]

Update restarts

Somewhere I think I’ve published a note about an anomaly that’s been bugging me since at least Oracle 10g – but if it is somewhere on the Internet it’s hiding itself very well and I can’t find it, though I have managed to find a few scripts on my laptop that make a casual reference to the side effects of the provlem. [Ed: a tweet from Timur Ahkmadeev has identified a conversation in the comments on an older post that could explain why I thought I’d written something about the issue.]

Anyway, I’ve decided to create some new code and write the article (all over again, maybe). The problem is a strange overhead that can appear when you do a simple but large update driving off a tablescan.

Extending in-lists

A well known “limitation” of Oracle is that you can only have 1000 elements within an IN-LIST style expression in your SQL predicates. I use the quotes because I’ve always found that if you are heading into the territory where you need more than 1000 items in an IN-LIST, then it is often indicative of something else being wrong. For example, if the code is backing a user interface, then where in the design phase did someone not go “Whoa…we are going to have 1000 select-able elements on the screen?”

In any event, you can find many tricks and techniques out there on the intertubes about how workaround this issue, such as:

Quiz Night

Upgrades cause surprises – here’s a pair of results from a model that I constructed more than 15 years ago, and ran today on 12.2, then modified and ran again, then ran on 11.2.0.4, then on 12.1.0.2. It’s very simple, I just create a table, gather stats, then update every row.

Speaker info for Perth, Australia

I have just got back from the Groundbreakers Latin America tour, and the travelling was made so much easier with the information provided by the organizers. So with the APAC tour coming up, I felt duty bound to give some hopefully useful information about my home town in Perth.

Flying in/out

There are two airport terminals in Perth. In times gone by, these were known as the Domestic and International terminals because, as the names suggest, domestic flights within Australia landed at one, and flights from overseas landed at the other. Hence locals will still refer to the terminals as “domestic” and “international”. However, due to all sorts of politics and bickering between airlines, times have changed.