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October 2012

Does the Parse Time Increase Linearly with the Number Of Child Cursors?

In the last post I discussed a test case generating lot of child cursors. Today I wanted to show you, for the very same test case, that in 11.2 the parse time might increases linearly with the number of child cursors per parent cursor. This is the expected behavior. In fact, to check whether an already available child cursor can be reused, the list of child cursors must be scanned. And, in case no one of the already available child cursors is compatible, every entry needs to be probed.

Skip Scan

A recent question on OTN asked how you could model a case where Oracle had the choice between a “perfect” index for a range scan and an index that could be used for an index skip scan and choose the latter path even though it was clearly (to the human eye) the less sensible choice. There have been a number of wierd and wonderful anomalies with the index skip scan and bad choice over the years, and this particular case is just one of many oddities I have seen in the past – so I didn’t think it would be hard to model one (in fact, I thought I already had at least two examples somewhere in my library – but I couldn’t find them).

Oaktable World first 3 vidoes up

The first 3 videos of talks at Oaktable World are up:

Connor McDonald 11g RAC upgrade drama

Tanel Poder hacking session:

Tim Gorman on exchange partition

We still have more video material to come but only limited resources to go through and edit them.  Comment here if you are interested in help out edit video. For a list of talks see:



Movember at…

Movember is coming to…

You will be able to track my progress here:

If you can afford to make a donation, no matter how small, it would be much appreciated!

I’ll try and post a photo each day for the whole month, so you can see how bad I am at growing facial hair. :)



PS. I feel really nervous now. It’s suddenly become very real!

DOUG presentation on dbms_xplan

Please join us at the DOUG (DALLAS ORACLE USERS GROUP) Oracle Database Forum meeting on Thursday, October 25, 2012 from 5 pm – 7 pm.
Presented by Riyaj Shamsudeen, OraInternals, & Sahil Thapar:

“Out with the old way, Enter dbms_xplan: A Swiss army knife for performance engineers”

Rough outline:
(i) Ability to query access path from memory, AWR repository
(ii) Ability to use cardinality feedback method to understand access plan issues. Few tips from a real world experience will be provided too.
(iii) Ability to understand issues with database links etc.
(iv) Options such as ADVANCED, ALLSTATS etc
(v) Why should you choose dbmx_xplan over tkprof+sql_trace combination?
(vi) Disadvantages of dbms_xplan and a quick introduction to dbms_monitor.

Refreshments sponsored by me :)

oci-24550 [3221225477] [Unhandled exception: Code=c0000005 Flags=0

October 22, 2012 Lately, I have been busy with a couple of items that are not completely Oracle Database specific.  I tried experimenting with high definition 1080p security cameras.  After wasting an unacceptable amount of money to purchase two Y-Cam Wireless High Definition 1080p video cameras (model YCBLHD6), and spending in excess of 38 hours fighting with the cameras [...]

What Cancer Cannot Do

For my sister and all those who battle cancer...

Cancer is so limited...
It cannot cripple love.
It cannot shatter hope.
It cannot corrode faith.
It cannot eat away peace.
It cannot destroy confidence.
It cannot kill friendship.
It cannot shut out memories.
It cannot quench the spirit.
It cannot silence courage.
It cannot reduce eternal life.

Bring Your Own Device (BYOD) : Context is everything…

Bring Your Own Device (BYOD) is definitely an important issue for companies and IT departments, but what the vast majority of reporters and CEOs seem to forget is that context is extremely important.

Looking at this from a company perspective, when we are talking about phones and tablets, then BYOD is a pretty important issue. It seems to be creeping into the laptop side of business a little, but as far as desktops are concerned, BYOD it is virtually non-existent. So when Marc Benioff talks about the affect of BYOD on Windows 8 uptake I think he is living in some sort of dream land. I’m not suggesting Windows 8 will be a success in business, but it’s failure will not be down to BYOD.

ZFS Home Storage Network at 10GbE

About a year ago I've decided to put all my data on a home built ZFS storage server. The growing amount of devices around my household prompted for an easier and much faster way to share the data. Since then the box was happily serving both CIFS as well as iSCSI over 1GbE network without any issues.

I was keen on upgrading to 10GbE for quite some time as both my server as well as clients could easily saturate 1GbE link when ZFS had all the required data in ARC. 32GB RAM in my storage server usually left me with the ARC of about 20GB which in most cases happened to be enough to cache the entire workset I was working with. Bottom line is the box rarely had to touch the disk and even if it did there was 120GB L2ARC SSD to even the bumps capable of maxing out 1GbE link as well.

It so happened that I managed to get my hands on a pair of 10GBASE-T Emulex OCe11102-NT NICs which I bought at a significant discount.

WebLogic and Forms & Reports Services Articles Updated…

I ran through a Forms & Reports Services installation on WebLogic 10.3.6 this morning, so I made some minor tweaks to my existing 10.3.5 articles on that subject.

The current spin of Forms & Reports Services has a prerequisite check for 10.3.5, so you just have to turn off the prerequisites check using this.

$ ./runInstaller -ignoreSysPrereqs

Apart from that it’s pretty much business as usual.