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May 2013

The year of the “back-fill” author…

I recently filled in this years ACE Director self assessment survey. Among other things, as part of that process I check how many articles, blog posts and forum answers I’ve posted over the year.

Whilst getting these numbers I noticed about 50% of articles I put live this year weren’t promoted to the front page as new articles because they were “back-fill”, written on general topics that haven’t really changed over the years. Of the last 6 articles I’ve written, only 1 has made it to the front page as a “new” article. Some of these back-fill articles were prompted by answering readers questions and some by situations that have come up at work. They all go live on the website, but I’d feel silly posting them as a new article. :)

Using Optimizer Hints for Oracle Performance Tuning

My next Embarcadero sponsored webinar will be on May 14 and is entitled Using Optimizer Hints for Oracle Performance Tuning.

Register now!

SLOB

Anyone who has used Kevin Closson’s “Silly Little Oracle Benchmark” will want to know about his significantly updated SLOB2.

Webinars

Reminder

The “Smarter Stats in 11g” webinar is on tomorrow (Monday 10th):

Update:

I’ve scheduled a third time for the repeats of the free webinar  ”Smarter Statistics in 11g” on June 10th – 1:00 pm BST.  The 6:00 pm is already full, but there are still places on the 9:00 pm showing.  As before we’re using GoToWebinar as the supply mechanism, and we’ve limited access to 100 people (so if you do register and can’t attend, please remove yourself from the list). The recordings of the webinar will be available to registered listeners for 7 days after the event.

Links to register for the  event:

When does an Oracle process know it’s on Exadata?

When an Oracle process starts executing a query and needs to do a full segment scan, it needs to make a decision if it’s going to use ‘blockmode’, which is the normal way of working on non-Exadata Oracle databases, where blocks are read from disk and processed by the Oracle foreground process, either “cached” (read from disk and put in the database buffercache) or “direct” (read from disk and put in the process’ PGA), or ‘offloaded mode’, where part of the execution is done by the cell server.

The code layer where the Oracle database process initiates the offloading is ‘kcfis’; an educated guess is Kernel Cache File Intelligent Storage. Does a “normal” alias non-Exadata database ever use the ‘kcfis’ layer? My first guess would be ‘no’, but we all know guessing takes you nowhere (right?). Let’s see if a “normal” database uses the ‘kcfis’ functions on a Linux x64 (OL 6.3) system with Oracle 11.2.0.3 64 bit using ASM.

Watching the “CopyBack” progress of a new disk on an Exadata compute node

This is just a very small post on how to watch the progress of the “CopyBack” state of a freshly inserted disk in an Exadata “Computing” (database) node. A disk failed in the (LSI Hardware) RAID5 set, and the hotspare disk was automatically used. The failed disk was replaced, and we are now awaiting the intermediate “CopyBack” phase.

The current state of the disks is visible using the following command:

SLOB 2 — A Significant Update. Links Are Here.

BLOG UPDATE 2012.05.05: Updated the tar archive distribution file with some bug fixes.  Simply preserve your slob.conf file and extract this tar archive over your prior SLOB install directory.

BLOG UPDATE 2012.05.04: The PDF README will no longer be bundled in with the tar archive.

BLOG UPDATE 2012.05.03: First time visitors should see the introductory page for SLOB.

About SLOB 2
I’ve already socialized the SLOB 2 update via twitter and a lot of friends have had early access to the kit. So, this is just a very brief blog entry to point to SLOB 2.

v$lock

The problem of slow queries on v$lock just came up again on the OTN database forum, so I thought I’d better push out a post that’s been hanging around on my blog for the last few months. This is actually mentioned in MOS in note 1328789.1: “Query Against v$lock Run from OEM Performs Slowly” which points out that it is basically a problem of bad statistics and all you have to do is collect the stats.

May 22, 2013: Full day of Oracle hands on labs, free! (bay area)

MH900400379Oracle OTN is hosting a full day of  free*  hands on Oracle labs on May 22, 2013 in Pleasanton, Ca

Grouping Data Sets by Week Number of the Month

May 1, 2013 I saw a decent SQL brain teaser this morning in the comp.databases.oracle.server Usenet group.  The OP in the message thread is attempting to summarize data in one of his tables, with the summarizations broken down by month and then the week within that month.  Increasing the challenge, the OP required that the dates defining […]