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October 2012

Adaptive Log File Sync: Oracle, Please Don’t Do That Again

Disclaimer: much that follows is pure speculation on my part. It could be completely wrong and I’m putting it out there in the hopes that it’ll eventually be proven one way or the other.

VirtualBox 4.2.2 Released…

I knew there was something missing from my life. It seems ages since I’ve updated all my VirtualBox guest additions. :)

VirtualBox 4.2.2 is available, with the changelog and downloads in the usual place.

Happy upgrading.



How Many Children Can a Parent Cursor Have? 1,000,000?

The patch set includes a fix for bug# 10187168 which, in reality, is an enhancement request. Its purpose is to artificially limit the number of child cursors that a parent cursor can have. The concept is quite easy: when a parent cursor reaches _cursor_obsolete_threshold (default value is 100) child cursors the parent cursor is obsoleted and, as a result, a new one is created.

So, as of (or with some PSUs and bundle patches), the answer to the question is: 100.

OOW 2012 – The yearly AMIS Review from Oracle Open World and JavaOne

Yesterday (16th October), 10 days of the end of the yearly Oracle show in San Francisco, AMIS organized its ‘Review from Oracle Open World 2012′ session with an overview of news, trends, announcements, special finds and interesting rumors . This session was ‘sold out’ (even though it was free). For close to 4 hours, the …

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Philosophy 19

We’ve reached that time of year (Autumn, or Fall if you prefer the American term) when I’m reminded that tending a garden is like tending an Oracle database.

This is a picture of the oak tree on my front lawn, taken about 4 hours ago. Looking at it now it shows hardly any sign of the coming winter and little of the colour that let’s you know it’s preparing to drop its huge volume of leaves, but yesterday morning I spent the best part of an hour raking up leaves that had dropped over the course of the previous week.

Oracle exadata: pam and temporary user-lockout.

If you are administering an Oracle Exadata database machine, which base operating system image (the operating system version with which it system came) is Linux and version (current version is viewable with the command ‘imageinfo’, which needs root account privileges) or higher, and multiple users are accessing the system with password authentication, this blogpost might be an interesting read. Also, if you have witnessed temporary lockout of the oracle user, or other users: this blogpost describes the reason and a potential resolution.

Pluggable 12c

For anyone looking for information on 12c, there are several posts about OpenWorld at the dbi Services blog (see links at right). In particular there’s a summary post about the “pluggable database” describing how you could plug a database into a “container” database, clone it inside the container database, then unplug it and put it somewhere else.

When I heard about the feature, it crossed my mind that there were two “obvious” targets for this technology that Oracle had in mind – in no particular order:

Knowledge Spreading at Work…

During my PhD our lab would have Friday meetings where we would take turns (3-4 people each week) to stand up and talk about scientific papers we had read recently. It was on a rota, so you only had to speak about once a month, but I truly hated it. I would go as far as to say I preferred taking my turn to clean the hot lab (the room we did all the radioactive stuff in), even if my mate Big Steve had spilt stuff all over the place, which he did on a regular basis…

Fast forward the best part of 20 years and I’m pretty comfortable with this whole speaking thing, so I suggested it might be a good idea if we start some type of regular meeting at work to help with the knowledge spreading. I spoke to Connor McDonald about this a few years ago. It was something he used to do in a previous company…

Exadata Storage Indexes Part III – Similarities With Database Indexes (Same Old Scene)

As discussed previously, there are quite a number of differences between Storage Indexes (SIs) and Database Indexes (DIs). However, there are also a number similarities between both of them as well. The obvious one is that they’re both designed specifically to reduce the overheads associated with retrieving the required data out of the database. Both index structures provides […]