Cardinality and Indexes Explained

What is cardinality with respect to an indexed column? Well cardinality is just a measure of how unique the information is in a column. For most index types, unique values are good and repeated values are bad.

For example, with a telephone directory, the more unique a name is the faster you can identify the person you are looking for. A name like “John Smith” is likely to have many entries and thus require verification of unindexed data to resolve the correct entry for your search, whereas “Zaphod Beeblebrox”, would be relative simple to identify.

Thus having a high cardinality or relatively unique column values, is typically a positive thing, in terms of index efficiency anyway.

If Android is the UNIX of Mobile Than Would Apple…?

Most of us was expecting Android to become popular and to outsell iOS (this is currently true for the phones. I’m not sure about the tablets but give it a year or less) but not this fast. It is generating a lot of buzz and developer buy-in but there’s also some scepticism about its potential fragmentation. So the analogy that we keep hearing is “Will Android become UNIX of Mobile?”. And when I hear this I’m asking “Then would Apple build their next OS on Android?”.

JavaOne 2010 – Day 2

Another morning but the same ritual: Getting ready, a short walk to Hilton San Francisco, silencing the grumbling stomach with a carb-packed breakfast and a cup of coffee for the morning pleasure. All this before joining the thousands of techies to attend the morning’s first session kicking off at 8am.

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JavaOne 2010 – Day 1

JavaOne’s first official day started on a beautiful sunny morning, not that I could enjoy the sun very long. I was feeling jet lagged and, awake since 5am, I was ravenous by the time I entered Hilton. The good thing about this venue is that there’s always a Starbucks in proximity. There’s even one in Hilton. First things first, I got myself a cup of coffee and something to eat. The day started with the first sip from my decaf americano.

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JavaOne 2010 – Day 0

Here I am, in San Francisco again, after more than a year. More than a year, because, instead of choosing May or June as it used to be when JavaOne was Sun’s, Oracle went for a joint conference in September. Yes, this year’s JavaOne is a joint conference organized with Oracle Develop. I have nothing against September. They even say that in San Francisco they have late summers. And it is true that this first day is a very pleasant one: 21 C (70 F) degrees and partly cloudy. Much better than most days of late May or early June.

This year’s JavaOne is a big question mark in my mind and I’m guessing that I’m not the only one. Even the fact that Google pulled off the biggest Java conference alone would be sufficient to raise more than a few eyebrows. Most developers wouldn’t care who own or control Java. They’d like to do their jobs with the best tools on the best platform. They couldn’t care less who is at the driver’s seat. However, it gets very worrying for everybody when the platform that millions of developers are using to develop millions of systems all around the world is used as a tool during the technology giants’ arm wrestle contests. I understand that from a company’s point of view, it’s important to raise a leg on a few trees to mark the territory but Oracle shouldn’t forget that Java is the biggest thing they control now. This gives them a tremendous power. And as the saying goes, “With great power comes great responsibility”. I, just like everyone else, am hoping that Oracle is going to do a better job than Sun in guiding Java. If nothing else, I was very disappointed to see some very interesting sessions cancelled at the last minute. Some of these sessions are JavaOne regulars, like Joshua Bloch‘s Effective Java. As an organizer, this is a huge failure. You cannot afford to loose presenters like Google in the world’s biggest Java conference. You just can’t! The community doesn’t want to see Java fragmented. This means that Oracle should cease to act like a control-freak from day one. The Java community loves Google and I’m afraid if we have to choose, most of us would choose Google over Oracle. So alienating Google from Java is not in the best interest of Oracle either.

Mason Street Tent - JavaOne 2010

I was also worried about the venue. JavaOne was traditionally held at the Moscone Center. However this year, the sessions are taking place in Hilton and Park hotels. Even though I can see some positive points in the new venue (being just 20 yards from my hotel instead of 5-6 blocs – Hey! I’m not lazy! I enjoy walking in San Francisco. It’s just when you have a long day that starts at 8am and ends at 11pm, I can tell you that 20 more minutes of sleep are precious) I am wondering how this is all going to hang together. I am afraid that it is going to be hard to appreciate the size of and the participation in this year’s JavaOne.

Oracle also blocked Mason street just next to the Hilton and created a tented area for developers. Mason Street Tent covers the whole block length of the street and it looks like it is going to be the busiest place of JavaOne 2010.

The registration process went very smoothly. Typed the e-mail address and showed a picture-ID, everything was done in less than a minute. All around was Oracle’s red & black colours, which I like. The conference material looks also very nice. At least we have a nice notepad to take notes unlike the recent years.

Yes! It is this time of the year again. Downtown San Francisco will be invaded by people strangely wearing their badges all the time (in the streets, in the bed, under the shower…) and in all the coffee shops, bars and restaurants there will at least be a corner where tech talk bubbles up.

Let there be Java!

Fota Island Resort iPhone App Officially Launches

Cork’s five star Fota Island Resort is the first independent hotel in Ireland to launch an iPhone application. And what’s more, they’re using a branded version of DSI’s hospitality iPhone app to lead the charge in the Irish hospitality industry. The free Fota Island Resort iPhone app is available to download here – http://bit.ly/64MOXs

‘Phoenix House Guest Relations’ iPhone App Launches

Phoenix House, the 5 star luxury serviced apartments in London, officially launched their branded version of DSI’s hospitality iPhone app today.

Featuring an interactive map with local attractions, apartment information, and the latest news/twitter feeds, the ‘Phoenix House Guest Relations’ iPhone app provides a 24/7 hotel concierge to guests. Users can also explore Phoenix House and surroundings with a gallery of photos or take advantage of exclusive offers with click-to-call functionality. DSI provides an online content management application as standard with our hospitality iPhone app, giving Phoenix House full control of the content published.

Phoenix House Guest Relations iPhone App
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DeCare Systems Ireland’s Solution for the Hospitality Industry.

A few weeks ago a friend of mine who runs a 5 Star property of 33 luxury apartments in London’s fashionable Sloane Square asked me which is the best iPhone docking station on the market. He told me that he had received many requests from guests to have them in the rooms. After looking at a range of docking stations and what they could do for his guest I suggested he should think about an iPhone application.

After seeing how successful the DSI created “ideal a day” app is working for Avon representatives we decided to create something that would be unique in the hospitality industry. Continue reading