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April 2012

NVL2()

There are many little bits and pieces lurking in the Oracle code set that would be very useful if only you had had time to notice them. Here’s one that seems to be virtually unknown, yet does a wonderful job of eliminating calls to decode().

The nvl2() function takes three parameters, returning the third if the first is null and returning the second if the first is not null. This is  convenient for all sorts of example where you might otherwise use an expression involving  case or decode(), but most particularly it’s a nice little option if you want to create a function-based index that indexes only those rows where a column is null.

Here’s a code fragment to demonstrate the effect:

You don’t need an app for that… (browser stats)…

I’m getting a bit sick of reading about how not having a mobile presence is a big fail. Once again the marketing people take a one-size-fits-all approach and assume that if you are on the net, then people must want to use your services from mobile devices. This is utter nonsense. In reality, the need for a mobile presence depends very much on what services you are offering and who you are offering them to.

For example, look at the OS breakdown for my website over the last month.

IOUG Collaborate Deep Dive slides — Deploying Oracle Database 11gR2 for High Availability by Alex Gorbachev

Quick blog post from Collaborate 2012 in Vegas. I’m only doing one session this year but it’s a very long session — I’ve just done a deel dive on deploying Oracle Database 11gR2 for High Availability. It’s a broad topic and my plan was to focus a lot on basic concepts and how they are [...]

Rant – Unique means UNIQUE! Argh!

I’m not a die-hard “Queen’s English”, “thou shalt not split infinitives” type but I am sick of people miss-using the word Unique.

The word unique means being one of a kind, the only example, the singular occurrence, the absolute only one. One. Singular. Get it? Still don’t get it? Well it means….unique! As a word that has only one unequivocal meaning, “unique” pretty much bloody well is it, by it’s absolute definition. It’s a yes/no situation. If you are unique in some respect, it means you are the only one example.

Temporary Tablespace Storage Parameters – What is Wrong with this Quote

April 22, 2012 (Modified April 24, 2012) I had intended to finish assembling the second half of the “Oracle Database 11gR2 Performance Tuning Cookbook” book review, however my free time that may be dedicated to book reviews has been a bit limited lately (I have a review of another book started, but left untouched for [...]

Where is LOB data stored?

There was a question in Oracle-L about where is the LOB data actually stored (in the row or the LOB segments) and what are the exact conditions when a switch from one to another may happen. The documentation isn’t fully clear about this and the “4000 bytes” number may mislead people to think that you can store 4000 bytes of your data in a LOB item before it must move out-of-line.

Where is LOB data stored?

There was a question in Oracle-L about where is the LOB data actually stored (in the row or the LOB segments) and what are the exact conditions when a switch from one to another may happen. The documentation isn’t fully clear about this and the “4000 bytes” number may mislead people to think that you can store 4000 bytes of your data in a LOB item before it must move out-of-line.

Where is LOB data stored?

There was a question in Oracle-L about where is the LOB data actually stored (in the row or the LOB segments) and what are the exact conditions when a switch from one to another may happen. The documentation isn’t fully clear about this and the “4000 bytes” number may mislead people to think that you can store 4000 bytes of your data in a LOB item before it must move out-of-line.

Where is LOB data stored?

There was a question in Oracle-L about where is the LOB data actually stored (in the row or the LOB segments) and what are the exact conditions when a switch from one to another may happen. The documentation isn’t fully clear about this and the “4000 bytes” number may mislead people to think that you can store 4000 bytes of your data in a LOB item before it must move out-of-line.

Where is LOB data stored?

There was a question in Oracle-L about where is the LOB data actually stored (in the row or the LOB segments) and what are the exact conditions when a switch from one to another may happen. The documentation isn’t fully clear about this and the “4000 bytes” number may mislead people to think that you can store 4000 bytes of your data in a LOB item before it must move out-of-line.