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February 2016

Management Packs, Restricted Use Licenses and the Enterprise Manager

There was a question posted on Oracle-l forum today that should have a blog post for easy lookup for folks.

OUG Ireland

I’m chairing a Q&A session on the Cost Based Optimizer for OUG Ireland.

We will be copying the format we used for the UKOUG annual conference, with some questions submitted in advance and Martin Widlake on the door handing out 5×3 cards for the audience to supply questions as they arrive, then running around the room with a microphone reading out questions or getting the audience to reply to comments from the table.

If you’d like to submit a question in advance, email me, or post it in the comments section below.


Another RMOUG Training Days Success!

I’ve just returned from another post-RMOUG conference mountain trip and happy to say that another RMOUG Training Days conference has successfully completed.

Never rely on an assumed order

We’ve (hopefully) all had it drummed into us enough times – you cannot assume the order of results from queries unless you explicitly include an ORDER BY statement.

Here’s another trivial example of this- I was doing a little demo script for an AskTom question.

Here’s the script running in


A while back I did a blog post showing that when you have set a column to UNUSED, it still “counts” as a validation step when doing exchange partition.  So if you had a partitioned table that previously had a column set to unused, then the candidate table to be exchanged in also had to have undergone the alteration.  Just having the visible columns aligned is not sufficient.

In the comments, Sergey presented an interesting variation of this, which we will look at below

Updated BI Publisher material

Just a quick note to say the material covered on my BI Publisher page has been updated to include some links specific to EM13c. If you can’t be bothered heading over to that page, here are the two new links </p />

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Connect By

I received an email a couple of days ago that was a little different from usual – although the obvious answer was “it’s the data”. A connect by query with any one of several hundred input values ran in just a few seconds, but with one specific input it was still running 4,000 seconds later using the same execution plan – was this a bug ?

There’s nothing to suggest that it should be, with skewed data anything can happen: even a single table access by exact index could take 1/100th of a second to return a result if there was only one row matching the requirement and 1,000 seconds if there were 100,000 rows in 100,000 different table blocks (and the table was VERY big). The same scaling problem could be true of any type of query – and “connect by” queries can expose you to a massive impact because their run time can increase geometrically as the recursion takes place.

Advanced Oracle Troubleshooting - One Day Seminar, Moscow

I got invited by Luxoft Training to deliver my one day seminar "Advanced Oracle Troubleshooting" in Moscow end of March.

More details about what I cover in this seminar can be found here.

If you're interested, Luxoft Training has set up a page in Russian where you can find more details - but note that the seminar language will be English.

I’m not spamming your blog comments!

confused-panda-303949_640It has come to my attention that there is a new website in town that happens to have a URL extremely similar to mine. Literally one character different. The domain in question was registered on 3rd November 2015.

Let me first say, the site in question does not contain any of my content (*see update*) and as far as I know is not doing anything wrong from a content perspective. The reason I am writing this post is to protect myself.

Oracle DBA, IT Manager, or Something Else

February 14, 2016 In September 2014 I posted an article on this blog where I mentioned that I am the IT Manager and an Oracle Database administrator at a company that specializes in welding and machining very large metal parts – in the article I attempted a bit of humor while trying to explain a few items.  […]