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October 2012

Running Total

Here’s a question on OTN from a  SQL Server user that should prompt a few interesting ideas. Re-arranged and paraphrased it goes something like this:

In SQL Server I can write the following code:

DECLARE @Counter INT
SELECT @Counter = 0

UPDATE TempDB.dbo.TransactionDetail
SET @Counter = AccountRunningCount = @Counter + 1
FROM TempDB.dbo.TransactionDetail WITH (TABLOCKX)

What I want to do is more like this:

DECLARE @Total INT = 0
UPDATE StringOutput
set @Total = SumOfLength = @Total + ColLength
OPTION (MAXDOP 1)

How do I do something similar in Oracle ?

Scale Abilities Awarded Gold Partner of the Year

Scale Abilities is very proud to announce that we have secured first place (Gold) in the UKOUG Partner of the Year Awards in the Database category. Thanks go out to all our clients that voted for us, we really appreciate your support and hope that we continue to exceed your expectations moving forward. Our competitors in […]

New Version Of XPLAN_ASH Utility

A new version 2.0 of the XPLAN_ASH utility introduced here is available for download.You can download the latest version here.The change log tracks the following changes:- Access check- Conditional compilation for different database versions- Additional activity summary- Concurrent activity information (what is/was going on at the same time)- Experimental stuff: Additional I/O summary- More pretty printing- Experimental stuff: I/O added to Average Active Session Graph (renamed to Activity Timeline)- Top Execution Plan Lines and Top Activities added to Activity Timeline- Activity Timeline is now also shown for serial execution when TIMELINE option is specified- From 11.2.0.2 on: We get the ACTUAL DOP from the undocumented PX_FLAGS colu

My public appearances in autumn 2012

The era of different conferences before the end of this year is here.
Last week I was speaking at Slovenian Oracle User Group Conference in Ljubljana and later on in the same week at Croatian Oracle User Group Conference in Rovinj.

Here is the list of my forthcoming public appearances:

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
http://oaktableworld.com/video-connor-mcdonald-11g-rac-upgrade-drama/

Tanel Poder hacking session:
http://oaktableworld.com/tanel-poder-hacking-session-video/

Tim Gorman on exchange partition
http://oaktableworld.com/video-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:

http://oaktableworld.com/

 

 

Movember at ORACLE-BASE.com…

Movember is coming to ORACLE-BASE.com…

You will be able to track my progress here: http://mobro.co/timseanhall

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. :)

Cheers

Tim…

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