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April 2012

Upcoming Events

I'll be doing four public events in the next week and a half or so.

The first one is open to anyone - anywhere.  I'll be doing a live webinar on MAA - the Maximum Availability Architecture.  It will take place this Thursday April 12th at 10am PDT.  You should register online before then if you are interested.

After that, I'll be off to Belfast Ireland to do a repeat of what I presented at Oracle OpenWorld in October.  This will be done in conjunction with Oracle and the UKOUG.  See for details, it'll take place on Monday April 16th.

Column Groups - Edge Cases

Oracle 11g added Extended Statistics support for column groups in order to detect correlated columns for filter predicates using an equal comparison.

Note that Oracle 11g also added the ability to use the number of distinct keys of a composite index as an upper limit for the cardinality estimates for matching column predicates, which means that the optimizer is now capable of detecting correlated columns without the explicit addition of Extended Statistics / Column Groups.

Friendly Reminder - Free Webinar

This is just a friendly reminder that tomorrow my free Webinar on Cost-Based Optimizer Basics will take place at

Repairman Jack : Hosts

Hosts is the fifth book in the Repairman Jack series by F. Paul Wilson.

Jack is reunited with his sister, just as a new virus threatens to link all human brains into a single collective hive mind, turning the human race into a docile petri dish living for the greater good of the virus.

Perhaps it’s my mood, but this story is just a little too depressing for my tastes. I’m hoping the rest of the series won’t degenerate into this type of doom and gloom. It needs a little more wit and humor to lift it.



Stats Collection

This is just a temporary note to point you to a poll set up by Timur Akhmadeev to get an idea of how people are handling stats collection in newer versions of Oracle.



Here is a poll prompted by today twitter talks on the default METHOD_OPT value (which is ‘for all columns size auto’ since 10g) and automatic statistics gathering job (auto-task since 11g). CBO development team suggests to use the default job to gather statistics with default options. Do you use the job exactly this way with real production databases? I’m very interested to see some numbers. Please share the poll link so that more people vote. Thanks.

Do you think Dropbox are getting nervous about Google’s GDrive?

Just got this message today…

Hi Timothy,

You can now earn twice as much free space by inviting your friends!

For each friend that installs Dropbox, you’ll both get 500 MB of free space. You can earn up to 16 GB.

Invite your friends now!

Thanks for spreading the Dropbox love,
- The Dropbox Team

P.S. Already invited a bunch of people? Don’t worry! You’ll get credited for all of them.

Do you think Dropbox are getting nervous about Google’s GDrive? :)



2012年4月6日 Oracle OpenWorld Unconference presented by JPOUG 開催


・EC2上でRAC構築を無理やりやる。 無意味なのがおもしろい!

The latest website move…

Yesterdays move of the website went pretty smoothly from a technical perspective. I had done a trial run using a different domain name so I didn’t foresee any problems on that front. During the trial, the DNS propagation took less than an hour, but the real run took a little longer. Typical. :)

Let’s hope this marks the end of me harping on about hosting companies and website outages…



The proof is out there

I’d like to thank Jonathan Lewis for taking up my challenge and writing up a proof that there is indeed a formula that solves Cary Millsap‘s string problem for not just circles, but for any regular polygon.

Like Jonathan, I found the problem intriguing, and “wasted” a few hours on a Saturday afternoon discovering the formula.

This blog entry isn’t about the formula or proof — it’s rather about the process I used to discover it.

You see, I didn’t know that such a formula actually existed before I set out — but I was convinced that there might be. After all, it would be neat if there was one, wouldn’t it?