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June 2012

Kernel UEK 2 on Oracle Linux 6.2 fixed lab server memory loss

A few days ago I wrote about my new lab server and the misfortune with kernel UEK (aka 2.6.32 + backports). It simply wouldn’t recognise the memory in the server:

# free -m
             total       used       free     shared    buffers     cached
Mem:          3385        426       2958          0          9        233
-/+ buffers/cache:        184       3200
Swap:          511          0        511

Ouch. Today I gave it another go, especially since my new M4 SSD has arrived. My first idea was to upgrade to UEK2. And indeed, following the instructions on Wim Coekaerts’s blog (see references), it worked:

Introducing A LinkedIn Group For SLOB Users

This is just a very short blog entry to inform folks that there is an open discussion group over at LinkedIn for SLOB topics of interest.

The group can be accessed through the following link:  SLOB LinkedIn Group.

Ad: Mastering Oracle Trace Data

This is just a short post to point out that the company I work for, Trivadis, is organizing 3 classes with Cary Millsap. The topic, as the title suggests, is Cary’s 1-day class entitled “Mastering Oracle Trace Data”.

The following dates and locations are planned:

  • September 11, 2012 – Münich (DE)
  • September 13, 2012 – Zürich (CH)
  • September 18, 2012 – Vienna (AT)

For detailed information have a look to the flyer. Note that the early bird registration period, that entitles you a 15% discount, ends on August 1.

Simple SLOB Init.ora Parameter File For Read IOPS Testing

This is just a quick blog entry to show the very simple init.ora parameter file I use to stress simple read IOPS testing with SLOB.  On 2s16c32t E5-2600 servers attached to very fast storage this init.ora parameter delivers on the order of 275,000 physical IOPS with 64 SLOB sessions.

I’ll post an init.ora that I use for the REDO model and DBWR testing as soon as possible.

Thanks to Yury for the recommended hidden init.ora parameters to boost the ratio of db file sequential reads.

Additional information can be found here: README file.

Here is the init.ora:

Report Generators And Query Transformations

Usually the Cost-Based Optimizer arrives at a reasonable execution plan if it gets the estimates regarding cardinality and data scattering / clustering right (if you want to learn more about that why not watch my Webinar available at "AllThingsOracle.com"?).

Here is an example I've recently come across where this wasn't case - the optimizer obviously preferred plans with a significantly higher cost.

The setup to reproduce the issue is simple:

Repairman Jack : Bloodline

Bloodline is the eleventh book in the Repairman Jack series by F. Paul Wilson.

After taking a break from doing fix-its, Jack takes on a simple case for Christy Pickering. She is looking for dirt on her daughter’s boyfriend, who is twice her daughters age. Not Jack’s normal work, but it sounds simple enough, until the first guy Christy hired for the job turns up dead. As usual, nothing is ever simple for Jack…

Discovering More Work-Related Windows Apps…

I know it’s a little sad, but I’m kinda enjoying discovering new little apps for Windows to do all those things that come out-of-the-box on Linux. Don’t get me wrong, I’m not loving Windows, but enjoying the discovery process itself.

X Server

On a Linux desktop you don’t need to worry about this, as your desktop is already using one. To get GUIs on the remote server to run on the local desktop, you just need connect to the remote server using “ssh -X oracle@myserver.example.com”

On Windows you need some additional software. There are plenty of paid for options, like Exceed, but there are also some free options. Many moons ago I used to use Cygwin. It’s still around and still does the job just fine. Remember to install the Cygwin/X libraries. Once it’s installed, do the following:

Unique Fail

As in – how come a unique (or primary key) index is predicted to return more than one row using a unique scan, for example (running on 10.2.0.3 – but the same type of thing happens on newer versions):

Quiz: Mystery of Create Table Statement

Happy Friday! I thought I would jumpstart your creative juices with this little, really simple quiz. While it's trivial, it may not be that obvious to many. See if you can catch it. Time yourself exactly 1 minute to get the answer. Tweet answer to me @arupnanda

Here it goes. Database is 11.2.0.3. Tool is SQL*Plus.

The user ARUP owns a procedure that accepts an input string and executes it. Here is the procedure.

create or replace procedure manipulate_arup_schema
(
p_input_string varchar2
)
is
begin
execute immediate p_input_string;
end;
/

The user ARUP have granted EXECUTE privileges on this to user SCOTT. The idea is simple: SCOTT can create and drop tables and other objects in ARUP's schema without requiring the dangerous create any table system privilege.

With this, SCOTT tries to create a table in the ARUP schema:

Indexes vs. Full Table Scan: Picture vs. 1000 Words (Pictures Of Lily)

I’m in the process of writing a number of new presentations and in one I’ve included a favorite little graph of mine that I’ve used over the years to help illustrate the relationship between the cost of using an index vs. the cost of using a Full Table Scan (FTS). It’s occurred to me that I’ve never actually [...]