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Who Stole gettimeofday() System Calls From Oracle strace() sessions?

I've been meaning to write this blog post for a while now but never seemed to find the time. Hopefully this posting will be useful information for anyone that spends a lot of time tracing processes in Oracle from the Linux Operating System. I'm one of those people, so it was good to get to […]

Who Stole gettimeofday() System Calls From Oracle strace() sessions?

I've been meaning to write this blog post for a while now but never seemed to find the time. Hopefully this posting will be useful information for anyone that spends a lot of time tracing processes in Oracle from the Linux Operating System. I'm one of those people, so it was good to get to […]

System Architecture Series: Introduction to the Series and Licensing

This blog post is an introduction to a few posts that can be grouped together under the banner of 'System Architecture'. Specifically, I'm referring here to Oracle Database System Architecture, not system architecture in general nor 'Oracle architecture' in general, which is an ever-growing beast. In this series of posts, I will take at look […]

System Architecture Series: Introduction to the Series and Licensing

This blog post is an introduction to a few posts that can be grouped together under the banner of 'System Architecture'. Specifically, I'm referring here to Oracle Database System Architecture, not system architecture in general nor 'Oracle architecture' in general, which is an ever-growing beast. In this series of posts, I will take at look […]

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

count(*)

I came across a nice bit of code on OTN recently that someone had written several years ago (in 2007, in fact)  to demonstrate the different ways in which the optimizer would handle “select count({something}) from table;”. If you want to copy and repeat the test code, you may need to adjust it slightly – it references a type vc2s, which I changed to dbms_stats.chararray, and it references a plan table called toad_plan_table, which I replaced with references to the standard plan_table (getting rid of the truncate as I did so).

Friday Philosophy – Is the CBO becoming way too complex?

I was at the SIOUG annual conference in Slovenia this week (and a very good conference it was too) and I was watching a presentation by Christian Antognini about how the CBO learns by it’s mistakes. This was of course mostly about adaptive cursor sharing and cardinality feedback. Chris was also able to share a few tid-bits about 12c enhancements in this area. I can’t go into details, but basically it looks like the CBO is going to not only enhance those two features but there is a new one where the CBO can change the plan on the fly, as the same query progresses.

SSD

There’s never enough time to read everything that’s worth reading, so even though Guy Harrison’s blog is one of the ones worth reading I find that it’s often months since I last read it. Visiting it late last night, I found an interesting batch of articles spread over the last year about the performance of SSD – the conclusions may not be what you expect, but make sure you read all the articles or you might end up with a completely misleading impression:

OOW 2012 – And was there news on the XMLDB front…?

Just finished my Birds of a Feather XMLDB panel session in the Marriott Hotel and now looking back on an event full day. It all started of with a Keynote session with among others Mark Hurd. the most interesting bit, in my honest opinion, was the announcement of more details in Oracle 12c. I will …

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OakTable World 2012

This Monday Oct 1, 2:00-2:50PM I’ll be presenting at the OakTable World which used to be called as Oracle Closed World, this year it’s a full two-day conference with awesome speakers lineup and very interesting topics… you can just watch this video by Mogens Norgaard to know more about the roots of this very technical event.

My presentation title is “Where did my CPU go?” – monitoring & capacity planning adventures on a consolidated environment .. and If you love to hack the ASH and AWR data and curious about CPU capacity planning then you’re really going to enjoy this session.. it’s going to be all about CPU ;)