Oracle AWR Reports: When IOStats Lie

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If you’ve been unfortunate enough to follow my dithering on Twitter recently you’ll know that I’ve been lurching between thinking that there is and isn’t a problem with Oracle’s tracking of I/O statistics in its AWR reports.

I’m now convinced there is a problem, but I can’t work out what causes it… so step 1 is to describe the problem here, after which step 2 will probably be to sit back and hope someone far (more...)

New Cookbook: Oracle Linux 6 Update 5 within an Oracle VM Template

Oracle-VMI’ve posted a new installation cookbook for using Oracle within a virtual machine running on Oracle VM. Surprisingly, I was unable to come up with a satisfactory method of accessing external storage that did not involve the use of Oracle ASMLib

Oracle Linux 6 Update 5 within an Oracle VM Template


Filed under: Blog, Cookbooks, Database, Flash, Linux, Storage Tagged: cookbooks, database, oracle, oracle vm

Create Histograms On Columns That Already Have One

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The default value of METHOD_OPT from  10g onwards is ‘FOR ALL COLUMNS SIZE AUTO’.

The definition of AUTO as per Oracle documentation is  :
AUTO: Oracle determines the columns to collect histograms based on data distribution and the workload of the columns.

This basically implies that Oracle will automatically  create histograms on those  columns which have skewed data distribution and there are  SQL statements  referencing those columns.

However, this gives rise to (more...)

Oracle database operating system memory allocation management for PGA

This post is about memory management on the operating system level of an Oracle database. The first question that might pop in your head is: isn’t this a solved problem? The answer is: yes, if you use Oracle’s AMM (Automatic Memory Management) feature, which let’s you set a limit for the Oracle datababase’s two main memory area’s: SGA and PGA. But in my opinion any serious, real life, usage of an Oracle database on Linux (more...)

RAC and preventing Active Data Guard: My experiences

When you happen to have a customer that want’s to use Data Guard on Oracle RAC without a license for Active Data Guard then you might want to read this post.

You probably have searched on the internet (just like I did) and already found this nice post from Uwe: http://uhesse.com/2013/10/01/parameter-to-prevent-license-violation-with-active-data-guard/

If you haven’t already then go ahead and read it, but come back when you also use RAC.

I had set-up Data Guard between (more...)

RELY trumps DISABLE

Learning, relearning or unforgetting…

What value is there in a DISABLEd constraint?

This was a question on the OTN forums this week and a) my first reply was wrong and b) I couldn’t find a clear demonstration elsewhere.

The documentation is clear.

RELY Constraints

The ETL process commonly verifies that certain constraints are true. For example, it can validate all of the foreign keys in the data coming into the fact table. This means that (more...)

Oracle AWR Reports: When Averages Lie

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I was recently contacted by a customer who runs a busy ERP system on their Oracle database. Their users have been screaming for some time about unpredictable performance, where application screens which would usually open in under a second suddenly take an age. ERP systems are legendary for this, of course, because as each screen loads the application tends to fire off a glut of queries to populate all the various fields, graphs and so (more...)

Upgrade Oracle GoldenGate 12.1.2.0.x to 12.1.2.1.x

Recently, I’ve been engaged in a conversation on the OTN community pages about upgrading Oracle GoldenGate 12c from 12.1.2.0.0 to the 12.1.2.1.0.  During the discussion I mentioned that you can upgrade using the Oracle Universal Installer (OUI) that is now available with Oracle GoldenGate 12c.  The upgrade process I’m going to show you here is an in-place upgrade of Oracle GoldenGate 12c for Oracle Database 12c.

Note: (more...)

SQL*Plus / SQL*Net Dead Connection Detection

Recently I came across the situation where I knew for a fact that my sessions to the database where dead because I pulled the power plug out of my application server for a failover test. But the sessions stayed visible in the database and kept their locks therefor the failover failed.

Now how is that possible?

First let me sketch the layout of the setup.

Suppose you have a vendor supplied application that runs on their middleware. That (more...)

Securing Oracle GoldenGate Database Login in a Credential Store

Security is always a big deal.  In setting up Oracle GoldenGate the capture (extract) and apply (replicat) parameter files need to be configured to log in to the database which they will perform operations.  In order to do this the Oracle GoldenGate User name and password need to be provided in the parameter files.  Example 1 shows how the database login is traditionally done in a extract or replicat parameter file.

Example 1:

--Oracle Login
 (more...)

Postcard from Oracle OpenWorld 2014: The Oracle FS1 Flash Array

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A couple of weeks ago I wrote a post about my trip to Oracle OpenWorld 2014 and the surprise announcement of the Oracle FS1 Flash Array. I posted it on the Violin Memory corporate website here:

http://www.violin-memory.com/blog/postcard-oracle-openworld-2014-the-oracle-fs1-flash-array/

Follow the link to find out whether I thought it was the most amazing product in the history of storage, or simply a rehashed Pillar Axiom hybrid array with some SSDs and a ton of marketing.


(more...)

Patching Time

Just a quick note to point out that the October PSU was just released. The database has a few more vulnerabilities than usual (31), but they are mostly related to Java and the high CVSS score of 9 only applies to people running Oracle on windows. (On other operating systems, the highest score is 6.5.)

I did happen to glance at the announcement on the security blog, and I thought this short (more...)

Installing Oracle 12.1.0.2 on Windows 64bit

The following steps are what I did for installing 12.1.0.2 on Windows.

1. Download the Oracle installation ZIP files from the Oracle Downloads page.

DB Install 15

2. Unzip the two 12c downloads files into the same directory.

3. Go to the newly created directory (it is probably called 'database') and you will find a file called setup.exe. Double click on this file.

DB Install 1

After a couple of seconds you will see the Oracle Database (more...)

Découverte : Workshop Enterprise Manager

Oracle France propose début octobre un workshop permettant de découvrir; à travers 6 ateliers de manipulation,  la solution Oracle Enterprise Manager 12c Cloud Control.

Annonce : MySQL & Enterprise Manager

Oracle a annoncé l'extension des capacités d'Oracle Enterprise Manager à superviser des bases de données MySQL.

Plus d'informations :

Complément : Sauvegarder une instance dans le Cloud Publid Oracle

Depuis avril 2014, Oracle propose une solution de sauvegarde Cloud, appelée Oracle Database Backup Service :

https://cloud.oracle.com/database_backup?lmResID=1394421723860&tabID=1394421714895 


La console Oracle Enterprise Manager 12c vous permet de piloter vos sauvegardes et restaurations directement sur Oracle Database Backup Service.


Plus d'informations :


Oracle, Parallelism and Direct Path Reads… on Flash

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Guest Post

This is another guest post from my buddy Nate Fuzi, who performs the same role as me for Violin but is based in the US instead of EMEA. Because he’s an American, Nate believes that “football” is played using your hands and that the ball is actually egg-shaped. This is of course ridiculous, because as the entire rest of the world knows, this is football whereas the game Nate is thinking of is (more...)

Complément : Analyse des performances sur du long terme

Viewing ASM trace files in VIM: Which Way Do You Use?

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A couple of people have asked me recently about a classic problem that most DBAs know: how to view ASM trace files in the VIM editor when the filenames start with a + character. To my surprise, there are actually quite a few different ways of doing it. Since it’s come up, I thought I’d list a few of them here… If you have another one to add, feel free to comment. I know that (more...)

OTech Magazine – Summer 2014

OTech Magazine – Summer 2014

OTech magazineThe fourth issue of OTech Magazine, the independent magazine for Oracle professionals, is available. For the summer 2014 issue there are some more personal articles included. Titles vary from The Spiritual Programmer to The Next Generation: Oracle SOA Suite 12c and back via How to protect your sensitive data using Oracle Data Vault.

Download OTech Magazine – Summer 2014 here.

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