News, views, tips and tricks on Oracle and other fun stuff

Videos on Flashback in Oracle Database 10g and 11g

Dan Morgan, the author of Morgan’s library, has just posted three videos on Flashback in Oracle database 10g and 11g:

  1. Watch the FlashBack Database video (20 min) on how to return the database to a point in the past using either the SCN (system change number) or a specified time. Go to the FlashBack Database webpage on Morgan’s library to try the code yourself.

  2. Watch the FlashBack Drop video (11 min) on how to recover a dropped table. Go to the FlashBack Drop webpage on Morgan’s library to try the code yourself.

  3. Watch the FlashBack Query video (9 min) on how to run queries against the database at any specific time in the past. Go to the FlashBack Query webpage on Morgan’s library to try the code yourself.

These are excellent videos (with nice classical introductory music) and I hope that Dan will post more videos on more Oracle topics in the future.

Note: You need the free RealMedia Player to watch the videos.

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What’s new is important

What is the first thing you do when a new version of an Oracle database (or any software) is released? You immediately look for the “what’s new” document, right?

I believe that the “What’s new” document is very important because it informs you of new (or modified) features that is supposed to make your life easier and your applications more powerful.

Take advantage of “what’s new”. After all, you’re paying for these new features (I assume), so use them or lose them.

To that end, here is a list of “what’s new” links. They will take you straight to the corresponding section of the Oracle documentation:

What’s new in Oracle Database version:

What’s new in SQL in Oracle Database version:

What’s new in PL/SQL in Oracle Database version:

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DUAL behavior change

While reading the book Expert Oracle Database Architecture, I noticed a very important bit of information about the DUAL table. In 10g, Oracle does not do a full table scan on DUAL if it does not need to. This is not the case in versions prior to 10g. To illustrate: Continue reading…

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Insert into DUAL

On the Oracle-l mailing list, Jared Still posted a message about a little experiment he did which concluded that Oracle (10gR1) always makes sure that DUAL returns one and only one row even if it contains more than one row.

I have repeated the experiment on my Oracle 10g XE database (Important: Do not do this dangerous stuff on your production database. Never insert/delete/update DUAL): Continue reading…

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Comparison between MS SQL 2005 and Oracle 10g

I stumbled upon a a technical white paper that provides a feature comparison between MSSQL 2005 (Yukon) and Oracle 10g databases. Here are a few points I noted from the paper, quoting:
Continue reading…

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Free Oracle Database 10g

I bet that you did not believe your eyes when you saw the two words “Free” and “Oracle” right next to each other, did you? Well, it happened a few hours ago. Oracle has now a “freebie” database of the 10g version, the Oracle Database 10g Express Edition. So what is Oracle Database 10g Express Edition? According to this tutorial (via Sergio): Continue reading…

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Oracle Regular Expressions

If you want to improve your ability to search and manipulate character data, regular expressions, a notation for describing textual patterns, is for you. And if you have Oracle Database 10g, you’re in luck, as the regular expressions feature was introduced starting with that release. Here are a couple of links that will help you understand and use regular expressions in your Oracle code (courtesy of Robert Vollman):

  1. Article at
  2. Reference at
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