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...)
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...)
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...)
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...)
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...)
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 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...)
A fairly important question, and a little surprise, appeared on Oracle-L a couple of days ago. Running 220.127.116.11 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...)
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
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:
We are starting a limited publicly accessible download of a trial version of Delphix and lab.
If interested connect with me on linkedin (more...)
Using the RMAN command "validate (more...)
Just a quick note that I posted slides for the 2 talks I did at ECO in Raleigh this week:
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.
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.
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 18.104.22.168.0 on Linux, it should be applicable to 11.2 Clusterware as well. Oh and by Clusterware I (more...)
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...)
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.
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...)
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...)
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!