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August 2016

How Many ASM Disks Per Disk Group And Adding vs. Resizing ASM Disks In An All-Flash Array Environment

I recently posted a 4-part blog series that aims to inform readers that, in an All-Flash Array environment (e.g., XtremIO), database and systems administrators should consider opting for simplicity when configuring and managing Oracle Automatic Storage Management (ASM).

Delphix Sessions at Oracle Open World 2016!

Oracle Open World 2016 is almost here…where did the summer go??

Data Loss

Quite obviously (well its obvious to me!) one of the areas I am very interested in is data loss / data theft / data security and of course specifically Oracle security. We spend a lot of time looking at customers....[Read More]

Posted by Pete On 31/08/16 At 08:17 PM

Surprise Attack of the Nulls: Hidden Traps in the NOT IN

Eight in a series of posts in response to Tim Ford's #EntryLevel Challenge.

My Fear Nothing post last month introduced some of the trouble that nulls can cause by generating results that are counterintuitive to what you would expect from a superficial reading of a query. This month we’ll go deeper into the rabbit hole, because the situation with nulls is rather worse than you might think. 

Let’s imagine for a moment that we’re interested in answering this business question:

Surprise Attack of the Nulls: Hidden Traps in the NOT IN

Nulls are tricky, and their effects go beyond query formulation to affect
even the very the business questions you’re able to pose. Business
questions must be formulated with nulls in mind. 

Read the full post at

How to fix a problem with the spfile in #Oracle

An invalid entry in the spfile may prevent the instance from starting up:

SQL> alter system set sga_target=500m scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00821: Specified value of sga_target 512M is too small, needs to be at least 1392M

The instance doesn’t come up! This is easy to fix without having to restore the spfile from backup:

SQL> create pfile='/home/oracle/init.ora' from spfile;

File created.

SQL> host vi /home/oracle/init.ora

Now correct the value in the text file. I just removed the sga_target parameter from it here. Then

An excellent review of where we are, where it all came from, and where we are going‏

About the book he reviewed for the August 2016 issue of the NoCOUG Journal, Brian had this to say:

“You should read this book. If you are starting out in a database-related career—which I think includes most, if not all, programming jobs—or if you are changing fields within the broader database field, the information in this book will be very helpful in the interview and on the job. I learned a great deal about things that I had already heard about along with many others that I have never heard of. Of all the books I have reviewed over many years, this is one of the very few that I think everyone could benefit from. I don’t think I’ve read a database book that presented so much material that was new to me in such a short time. This book is an excellent review of where we are, where it all came from, and where we are going.

Conference Report: NoCOUG 2016 summer conference at Chevron

The Northern California Oracle Users Group (NoCOUG) is a volunteer-run 501(c)(3) organization and the longest-running Oracle users group in the world. It organizes a full-day conference every quarter and publishes a quarterly Journal. The summer conference at Chevron was the 119th quarterly conference organized by NoCOUG.(read more)

A very gentle introduction to Oracle PL/SQL programming for beginners

PL/SQL offers the entire suite of structured programming mechanisms, such as condition checking, loops, and subroutines, as shown in the following figure. (read more)

A day in the life of a problem solver

P.O.I.S.E.D. is the acronym I invented for the performance tuning method described by Chris Lawson in The Art and Science of Oracle Performance Tuning; it stands for Problem, Observation, Interpretation, Solution, Execution, and Documentation.(read more)