V00D00 & APUD

Direct path insert and IOTs

(Please tell me that I’m not the only one who thinks "Index Organized Table" instead of "Internet Of Things" when hearing IOT…) This post is inspired by Connor McDonald and his blog post from a year ago about direct mode operations and IOTs. You can read it here: https://connor-mcdonald.com/2016/07/04/direct-mode-operations-on-iots/amp/ While writing a redo parser for […]


rollback internals

While researching redo log internals for V00D00 we had to face the fact, that we know shit about real transactional behavior. When I say "real", I mean – under the hood. Even with a very simple stuff like COMMIT and ROLLBACK we were constantly amazed by the internal mechanisms. Today let’s take ROLLBACK under the […]


How Oracle stores numbers internally

Before you proceed, please check out this short article written by Tanel Poder: http://blog.tanelpoder.com/2010/09/02/which-number-takes-more-space-in-an-oracle-row/ In the documentation, you can find the following explanation about the internal numeric format: Oracle stores numeric data in variable-length format. Each value is stored in scientific notation, with 1 byte used to store the exponent and up to 20 bytes […]


When UPDATE becomes an INSERT

During a research for VOODOO, we came across a lot of interesting stuff inside REDO. One of my favourites is an UPDATE, becoming an INSERT 🙂 So let’s see what has happened – I performed the following update on a sample table: The regular dump of redo log with an UPDATE looks like this: In […]


POUG voucher – contest

Contest time! I had a cool function in my database: When executed, it returned a -15% voucher for POUG conference. And POUG is a REALLY COOL confernece 🙂 Check it out: poug.org The problem is that I was cleaning my training database and dropped the function by accident. Fortunately, I have archivelogs and I wrote […]


How to recover a dropped package from archivelogs – based on research for VOODOO engine

Sorry for long time without post, but we are writing with Marcin Rydz a new heterogenous replication product based on archivelogs and it’s consuming a looooooot of our time 🙂 Yes I know it’s nothing new on the market. There are other cool products and I know they’ll be probably be better. But we want […]


ODBV improvements

Thanks to suggestions made by Frits Hoogland, I made some improvements to the ODBV. The new version can be found here: http://ora-600.pl/oinstall/odbv.x86_64 The changes are: Recognition of first, second and third level bitmap block Recognition of pagetable segment header Block number ranges on the left side The blocks will be coloured properly to belonging segment. […]


back to the basics: ALTER TABLE MOVE vs SHRINK

It’s time for the next article with ODBV visualisation 🙂 This time let’s examine the difference between move and shrink – this is very common question on a lot of trainings. You can find a lot of great articles in the Internet regarding this subject but I think that visualisation really helps to understand what […]


back to the basics: truncate table reuse storage vs drop storage

From time to time I get questions on my trainings, what is the difference between TRUNCATE TABLE and TRUNCATE TABLE DROP STORAGE… well, there is no difference because DROP STORAGE is default 😉 DROP STORAGE Specify DROP STORAGE to deallocate all space from the deleted rows from the table except the space allocated by the […]


Oracle Database Block Visualizer

Recently I wanted to demonstrate to some people on my training, how Oracle database maintains blocks in a datafile – what happens after truncate, truncate with drop storage clause, delete, regular insert, direct path insert and so on… I didn’t find any tool for that so I’ve written my own. It’s core code is based […]


OTN Appreciation Day : pragma UDF

Joining the OTN Appreciation Day 🙂 I really like the new pragma UDF feature for PL/SQL – it makes me believe that context switches will be less painful in the future 🙂 I wrote a little bit more about it here: http://blog.ora-600.pl/2015/10/29/oracle-12c-pragma-udf-the-truth/ And Martin Widlake wrote a lot about it here: https://mwidlake.wordpress.com/2015/11/11/pragma-udf-some-current-limitations/


Using DTrace to understand why PL/SQL packages can be faster than stored procedures (kgiPinObject)

I know – everyone knows, that PL/SQL packages are faster than stored procedures. If you’ll ask anyone at the training or in your dev team "what is better" – you’ll (almost) always hear: PL/SQL packages. But why exactly? The documentation says: The first time you invoke a package subprogram, Oracle Database loads the whole package […]

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