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March 2012

OUGN 2012 First Day – First Panic

I’m not really one for blogging about conferences – I mean who cares what someone else saw being presented? But this is the first time I have stopped moving long enough (and been in contact with the internet world) to blog and my brain is too fried to do a technical one.

Repairman Jack: All The Rage…

All The Rage is the fourth book in the Repairman Jack series by F. Paul Wilson.

There is a new designer drug in town. In the right dose it makes you assertive and confident. Too much and you become a savage killer. What seems like an innocent case for Jack, turns into a life or death situation for him and the people he loves.

A pretty neat romp that follows on quite nicely from the previous books…

Cheers

Tim…

RAC Attack at OUGN 2012

Quick post to bring the Virtual Box PDF to the attendees. Follow this link to get the instructions

RAC Attack Using VirtualBox

UPDATE

This post was the best way to get the PDF instructions to participants of the OUGN 2012 RAC Attack seminar without too much effort on our side. If you have since then used your favourite search engine and ended up here in the hope that there is an interesting story please navigate here instead:

http://martincarstenbach.wordpress.com/2012/03/26/ougn-spring-meeting-2012/

Thanks for passing by!

Sail Away, Sail Away, Sail Away

I’m just doing some last minute preparation for the Norwegian User Group Spring Seminar. This is quite a large conference with 5 concurrent streams and a very good line-up of presenters. You can see the agenda here.

What is also a little unusual about this conference is that it is mostly on a boat, or rather a ship. When I was first asked if I would put forward a talk or two I declined – as I am very prone to being sea-sick. Truls Bergersen, who helps organize the event, got in touch with me a few weeks later and said “we are doing a day on land first, do you want to present then?”. Sure! That would be great! So I am, I’ll be doing my talk on Index Organized Tables once more {and then I think I’ll put it to bed for a couple of years}.

Two things I learned this week...

I often say "I learn something new about Oracle every day".  It really is true - there is so much to know about it, it is hard to keep up sometimes.

Here are the two new things I learned - the first is regarding temporary tablespaces.  In the past - when people have asked "how can I shrink my temporary tablespace" I've said "create a new one that is smaller, alter your database/users to use this new one by default, wait a bit, drop the old one".  Actually I usually said first - "don't, it'll just grow again" but some people really wanted to make it smaller.

Now, there is an easier way:

http://docs.oracle.com/cd/E11882_01/server.112/e26088/statements_3002.htm#SQLRF53578

Using alter tablespace temp shrink space .

Website Server Move (wrap-up)…

Followers of this blog, Twitter or Google+ can’t help but have noticed me moaning about my hosting provider (Fasthosts). My site was moved on to a new server (by accident) in December:

Since then I’ve been having assorted rants on G+ and Twitter because the site has been up and down a lot.

Obsolete cursors

In the previous post I wrote about strangely behaving V$SQL. For some reason there were duplicate rows leading to wrong results issue when running DBMS_XPLAN.DISPLAY_CURSOR for a particular child cursor. I tried to reproduce the issue using simple test case – and it was reproduced.

Here it is. I’m starting to execute a simple query against DUAL while constantly changing optimizer environment, forcing Oracle to build a new child cursor for each execution:

Indexed Organized Tables – An Introduction to IOT Secondary Indexes (A Second Face)

Man, its been ages since I had free time to update the blog, what with birthday parties to organise, Roger Water concerts to attend and Radiohead concerts in the planning !! OK, time to take an initial look at Secondary Indexes for Index Organized Tables (IOTs). If the IOT needs to be accessed via the Primary Key (PK) column(s), [...]

No more excuse not to use large pages in Linux

This is a very quick post to remind users of the importance of large pages. Before 11.2.0.2 it was a little more elaborate process to determine the number of large pages to be set aside for Oracle, but now it’s so simple there isn’t any more excuse not to use large pages. If you have > 16G SGA and lots of processes, check the impact of large pages in /proc/meminfo before and after. By implementing large pages at a former company I reduced the page tables overhead from 20G (60G sga, processes set to 1000, most often around 800 sessions connected) to a fraction of that number.

Here is why you can’t hide anymore:

Oracle Linux 5.8 and UDEV issues…

I just did an update from Oracle Linux 5.7 to 5.8 on one of my VirtualBox RAC installations and things are not looking to clever at the moment. After a reboot, the ASM instances and therefore the database instances wouldn’t restart. A quick look showed the ASM disks were not visible. On this installation I was using UDEV, rather than ASMLib. In checking the UDEV rules I noticed the scsi_id command on OL5.8 doesn’t report an ID for partitions on disks, only the disks themselves. For example, on OL5.7 I get this,

# /sbin/scsi_id -g -u -s /block/sdb/sdb1
SATA_VBOX_HARDDISK_VBd306dbe0-df3367e3_
#

On OL5.8 I get this,

# /sbin/scsi_id -g -u -s /block/sdb/sdb1
#

If I run it against the disk, rather than the partition it works fine.