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September 2013

Bitmap / Btree

Here’s a little note that came about after I tweeted an idle thought on Twitter yesterday

  • 12c allows you to have multiple indexes on the same columns on a table, although only one of them is allowed to be visible at any one time – you can do the same with any recent versions of Oracle “almost”, and without the invisibility requirements. (Thanks to Jason Bucata for suggesting the critical detail on this one.)
  • 12c allows you to have “partial” indexing on partitioned tables -  you can do the same with earlier versions of Oracle “almost” but only if the indexes are local indexes or globally partitioned.
  • 12c doesn’t officially allow you to create an index that is a bitmap in the past and a btree in the present (yet) – although you can almost do this in any recent versions of Oracle.

How to use (almost) the same column definition for two indexes on the same table:

Insync 13 Brisbane

Just a quick note to let you know I’ll upload the slides in the next few days

Endymion

Endymion is the third book in the Hyperion Cantos series by Dan Simmons.

After finding the last book a little patchy at times, this one returned to the same sort of pacing and thrust that made me love the first book. This story picks up nearly 300 years after the last one ends. The daughter of one of the characters from the previous book entered one of the time tombs and appeared in Hyperion 274 years later. Since then things have changed throughout the former web worlds and the church has a vested interest in keeping things the way they are. The last thing they need is a little girl, with the power to topple their stronghold on the galaxy, messing things up for them.

Oracle Cloud Control EMCLI : First Thoughts

Whilst waiting for a new version of Cloud Control, which will hopefully include my job scheduler enhancement requests, I decided to see if I could solve my problem using the command line interface (EMCLI). That spawned this very basic article.

I was initially really excited by the EMCLI, planning to pretty much replace my job creation with EMCLI scripts, but there seem to be a bunch of discrepancies with the EMCLI compared to the regular Cloud Control interface. Now I admit I’m a newbie at this, but here’s what I’ve seen so far.

10053 Trace Files - Global Stats on Partitioned Tables

One of the reasons why it's taken a while to get around to the next 10053 trace file post (apart from the more human reasons I talked about here) is that I'd planned to show how 10053 trace files can show whether the CBO has used Global Statistics on Partitioned Tables or not, which is the example that I used the first few times I gave the 10053 presentation.

Blogging

I think it was Andy C who first mentioned to me that one of the golden rules of blogging was never to apologise or justify your reasons for not blogging. I guess it's because so many people do it so often that it becomes tedious. But my blogging output has been so woeful in the past year or so that I thought it worth mentioning at least one reason why and what I might do to encourage myself to write more useful posts.

The Story of Two Boats and Why Justin Bieber Owes Me £120* (Part 2)

So why does Justin Bieber owe me £120?

Histograms

In case you’re not following me on Twitter (@jloracle) where alerts from WordPress are posted automatically, I’ve just published the first of a short series on histograms on AllThingOracle. Part 2 is scheduled to come out around 16th Sept.