ORA-01555 Snapshot Too Old and Delayed Block Cleanout

The ORA-01555 error (snapshot too old) normally occurs when you try to query a table whilst it’s being changed. If the necessary undo to provide a read-consistent view of data is no longer available, then an ORA-01555 error will occur. This is typically due to bad design practices such as fetching across commits. However it is possible to encounter the same error when the table is not being changed. This is due to a database (more...)

Friday Philosophy – Is Dave Productive?

How do I know if Dave is doing his job properly? If I am his (or her*) manager, what techniques can I use to ensure I am getting my pound of flesh out of this worker drone in return for the exorbitant salary my company puts into said drone’s bank account each month?

Well, as a start there is my last Friday Philosophy all about analysis of work profile via auditory analysis of input devices (more...)

AUSOUG conference Perth

The annual two day AUSOUG conference in Perth is well underway, and so far, its been a wonderfully successful event. In particular, we Australians are notorious for not really getting into the networking thing, so conferences often have a lot of ‘awkward silences’ when sessions are not on, and we are meant to be (god forbid) *talking* to each other :-)

But this year has been different. Lots of banter, lots of discussion. Also, the (more...)

A Summer at CERN: Evaluating OpenStack Trove as DBaaS Solution

I have been one of the 23 students participating in the CERN openlab summer student programme this year. Like two of my fellow students in the database group, Sneha and Anti already did, I want to share some insights into the project I worked on and in general about my experience with the summer programme. Thus, the post is divided into a general part and a technical part, which will sum up what I (more...)

About Oracle’s Code of Ethics, MOS Confidentiality Clause, and Content Stolen from My Website

I strive to keep the number non-technical posts on this blog to the minimum. However, there are days when a non-technical post has to be written. This is one of such days.

Oracle Corporation, concerned about legal and ethical issues, not only provides to its employees a document entitled Code of Ethics and Business Conduct, but also expects that every employee adheres with the standards that the document sets. For the purpose of (more...)

A simple 12c query with a cool result …

Its not immediately obvious the significance of this query…but trust me…you’ll love it :-)

SQL> select table_name, column_name from dba_tab_cols
  2  where column_name like '%_VC' escape ''
  3  and owner = 'SYS'
  4  order by 1,2;

TABLE_NAME                     COLUMN_NAME
------------------------------ ----------------------
ALL_CONSTRAINTS                SEARCH_CONDITION_VC
ALL_VIEWS                      TEXT_VC
CDB_CONSTRAINTS                SEARCH_CONDITION_VC
CDB_VIEWS                      TEXT_VC
DBA_CONSTRAINTS                SEARCH_CONDITION_VC
DBA_VIEWS                      TEXT_VC
INT$DBA_CONSTRAINTS            SEARCH_CONDITION_VC
INT$DBA_VIEWS                  TEXT_VC
INT$INT$DBA_CONSTRAINTS        SEARCH_CONDITION_VC
USER_CONSTRAINTS               SEARCH_CONDITION_VC
USER_VIEWS                     TEXT_VC

What Day Is It If You Only Specify The Time?

What is the date if you only specify the time when you populate an Oracle date column (or variable)?

That was the question that came up a few days ago in the little DBA team I am currently working in. Of course, the question was posed by the “junior” (who is damned smart at this stuff as he keeps asking questions like that) and the answer from us two old hands was… “Ohh!… hang (more...)

Cardinality Feedback

A fairly important question, and a little surprise, appeared on Oracle-L a couple of days ago. Running 11.2.0.3 a query completed quickly on the first execution then ran very slowly on the second execution because Oracle had used cardinality feedback to change the plan. This shouldn’t really be entirely surprising – if you read all the notes that Oracle has published about cardinality feedback – but it’s certainly a little counter-intuitive.

Of course (more...)

Gambrinous

Wednesday’s word is Gambrinous, meaning full of beer, allegedly named after a Flemish King who is said to have invented beer.
 
Use: It was difficult to determine the most gambrinous group. Oakies, ACED, or Oakies ∩ ACED. However, it was not Oakies ∩ ACED ∩ BARBIGEROUS individuals, who tend to stick to cider.
 
 


Filed under: Prevarication

#CloneAttack online ! (and in person at #ECO14 & #DOAG14)

I’ll be at #ECO14 today in Raleigh,NC. Catch me in person to get a copy of #CloneAttack. I’ll also be at #DOAG14 in Nuremberg Nov 18-20 running an official #CloneAttack along side of #RacAttack and #RepAttack. Will also be at #BGOUG in Sofia Bulgaria Nov 14-16.

For online #CloneAttack info read on:

Screen Shot 2014-09-24 at 9.41.34 AM

We are starting a limited publicly accessible download of a trial version of Delphix and lab.

If interested connect with me on linkedin (more...)

The Importance of Backups (A Cautionary Block Recovery Tale)

Just wanted to share a quick story with everyone. As I was in the airport waiting to fly to Oracle OpenWorld this year, I noticed a flurry of emails indicating that part of our storage infrastructure for our standby production database had failed. Long story short, my co-workers did a brilliant job of stabilizing things and keeping recovery working. However, we ended up with more than a few block corruptions.

Using the RMAN command "validate (more...)

ECO 2014 Slides

Just a quick note that I posted slides for the 2 talks I did at ECO in Raleigh this week:

Keynote: Creative Problem Solving (for Oracle Systems)

In-Memory In Action (without Tanel Poder) :)

Great crowd. I really enjoyed myself.

Note: You can also find other presentations on my Whitepapers/Presentations page via the link at the top of the screen.

Slides from OUGE Meetup #3

I gave a talk about my highlights from Oracle Open World 2014 and how to use CloneDB in Oracle User Group Estonia Meetup #3. It was a really good meetup and thanks to everybody who attended.

Here you can find the slides

Little things worth knowing: ORACLE_SID, instance_name and the database names in Clusterware

If you ever wanted to know how Clusterware works with registered database resources, read on! It takes a little while to get your head around the concepts of the ORACLE_SID, the instance_name and the database name as well. And how Clusterware deals with all of them. Although this post has been written on 12.1.0.2.0 on Linux, it should be applicable to 11.2 Clusterware as well. Oh and by Clusterware I (more...)

DBMS_SYSTEM.KCFRMS

I read about this in the book advertised at the end of this post. It was tested on Oracle 11.2. V$SESSION_EVENT holds similar information to V$SYSTEM_EVENT but it is broken down by session (only currently logged in sessions appear - there is no history). There is a MAX_WAIT column which shows the maximum time a session has had to wait for a particular event.There is no timestamp on this so you cannot tell (more...)

Life of an Oracle I/O: tracing logical and physical I/O with systemtap

Topic: This post is about tracing logical and physical reads in Oracle using systemtap. You will find a few examples illustrating the main mechanisms used by Oracle to do physical and logical I/O and you will learn how to build systemtap scripts to further explore and troubleshoot Oracle I/O.

Introduction: Performing input/output to and from the storage media, i.e. physical I/O, is one of the critical tasks underlying all database engines. When accessing data (more...)

Oracle DBA job in Tempe, Arizona

We still have a position open on our Oracle database team here in Tempe, Arizona.  Here is the link with an updated job description: url

We have a great team and would love to have a new member to join us.

-Bobby

How to Find Blocking Sessions in Enterprise Manager Cloud Control 12c

My friend Franck Pachot noticed that EM12c doesn’t show the blocking sessions across all RAC nodes. Let’s check if we can find them using EM12c. I have connected to first node of our RAC database, created a sample table, inserted a row, committed, and then deleted the row. While the session is open, I opened another terminal, connected to second node and tried to delete the rows in same table so my second session started (more...)

Jonathan Lewis explains Delphix

OOW 2014 was the best so far for me and a whirl wind.  After not having a presentation accepted since I left Oracle 10 years ago, I got not only a presentation accepted but 3 presentations accepted. Woohoo! Two of my presentations are available on youtube at

On top of that with the awesome support of the Oaktable, Delphix, Pythian and Enkitec , I was able to secure a (more...)

Oracle Enterprise Manager 12c Command Line Interface is Available!

The new Oracle Enterprise Manager 12c Command Line Interface book is available via a number of locations, including Amazon and directly from Apress.  If you are an EM12c fanatic or just learning and want to learn more, consider the new book that will show you why the command line returns the DBA to the golden age, empowering Enterprise Manager to script and enable tasks at a global level!

9781484202395HiRes



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