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April 2014

An accusatory error message

I found this hilarious

SQL> startup
ORACLE instance started.

Total System Global Area 1469792256 bytes
Fixed Size                  2402776 bytes
Variable Size             536872488 bytes
Database Buffers          922746880 bytes
Redo Buffers                7770112 bytes
Database mounted.
ORA-19821: an intentionally corrupt log file was found

Really ? I intentionally corrupted my log file ?  I dont think so !


SQL injection

Another big public username and password leak…

Some good reading on how it was done, and thus ensuring your code isn’t prone to SQL injection here:

Pluggable database and restricted sessions

Once you get into pluggable database territory, you might need to check your usage of "alter system enable restricted session", because unless you’ve patched, there’s a little bug which lets you enable restricted session, but wont let you get out of it ! :-)

For example:

SQL> alter session set container = pdb12;
Session altered.
SQL> alter system enable restricted session;
System altered.
SQL> select logins from v$instance;
SQL> alter system disable restricted session;
alter system disable restricted session
ERROR at line 1:

You can get out of the predicament, by force opening the pluggable database as shown below, but probably best to look at the latest 12c PSU, which contains a fix (unverified)

OUGN 2014

I had the pleasure of being a guest of the Norwegian User Group for the second year in a row on their famous cruise conference at the start of April. For a relatively ‘small’ conference (around 300-400 people), the array of quality speakers the group manage to get is always astounding.  Martin Nash, Cary Millsap, Tim Hall, Bryn Llewellyn, Martin Bach, Jeff Smith, Doug Burns to name just a few.  I gave a few talks which (seemed :-)) to be well received by the audience.

The conference runs like clockwork, and Oslo is a beautiful city to spend a day wandering around sampling the cuisine.  The only real challenge is the 45min timeslot for papers, whereas as most places I’ve spoken at allow 50-60 mins, so you’re presented with the tough choice of cramming your existing content into 45 mins, or deciding what must be pared out.

Collaborate14 Session: Cache Buffer Chains Demystified

Thank you all for coming to my session Cache Buffer Chains Demystified at Collaborate 14, especially for sticking around for a geeky topic like this to the very end. Much appreciated.

I was not aware that I would not be allowed to use my laptop; so I couldn't show all the demos I so carefully prepared. Please download the scripts and execute them yourself.

As promised, here are the materials I used in the session

The Slide Deck
The Whitepaper
The Scripts (this is a zip file; so right click and Save As ...)

Needless to say, your comments and feedback will be highly appreciated. And, yes, please don't forget to do the evaluation on the Collab Mobile App.

Maximum manageable storage in VMware versions


Maximum manageable storage per VM by ESX version

  • 4.1: 32TB (vmdk) / 120TB (RDM)
  • 5.0: 60TB (vmdk) / 3.75PB (RDM)
  • 5.1: 60TB (vmdk) / 3.75PB (RDM)
  • 5.5: 3.63PB (vmdk) / 3.75PB (RDM)

Note that the 60TB limit for 5.0 and 5.1 requires Update 1. Without this the limit is 24TB.

Oracle RMAN Restore to the Same Machine as the Original Database

Among the most critical but often most neglected database administration tasks is testing restore from backup. But sometimes, you don’t have a test system handy, and need to test the restore on the same host as the source database. In such situations, the biggest fear is overwriting the original database. Here is a simple procedure you can follow, which will not overwrite the source.

Collaborate14 Session: The Art and Science of Tracing

Thank you all for coming to my session "The Art and Science of Tracing" at Collaborate 2014. As I mentioned, I prepared a full session even though this is supposed to be a quick tip. I hope you enjoyed it and get the value from the full presentation deck.

You can download

The slide deck
The scripts (this is a zip file. Right click and then Save As ...)

As always, your feedback will be immensely appreciated.

IOUG Collaborate 2014 presentations are online!

This is a small announcement that the slides of all of my four presentations for IOUG Collaborate 2014 are online in the ‘whitepapers and presentations’ section of this blog.

Presentation Slides for IOUG Collaborate

I know that folks have been having some challenges downloading my slides from Collaborate for a couple of my sessions and I know I’ve received errors when updating two of them the other day, so I’ve added them to my slideshare location for your convenience.