Opinions, Expertise, Passion.

I’ve done some work previously in XSLT to nicely format XML output within a browser.

Presently, some code I’m working with also does this transforming of an XML output via XSLT into a HTML file. I wanted to modify the XSLT, but found I’d made an error, so without having to pre-configure data and run the process every time every time in a more timeconsuming iterative debugging approach, I was able to do the following manually.

Having an XML file called example.xml and an XSLT file called example.xslt, by adding the second line below manually to the XML file I was able to then render the XML file in a Browser, which then reported the error enabling me to easily correct.


<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type=”text/xsl” href=”example.xslt”?>
…


It would have been nice if the browser could accept this for the XML file without the need to manually modify it. There probably is a better way, or a more specify XML GUI tool, but the time to find this out, maybe next time.

Here is a Beginner XSLT reference.

This is an interesting article How Google can make - or break - your company. The plight of a small business that overnight lost it’s high free search results and in the coming months say a 20% drop in sales.

The official response “Just as the web changes constantly, Google continues to modify and refine our algorithms to improve the quality of our objective search results.”

The comment made by the small business “It’s like owning a shop on a busy street corner where all the pedestrians suddenly and mysteriously vanish.” That’s gotto hurt.

The article also delves into a lot more, an interesting read.

While in Singapore earlier in the Year (Yes, I’m very slack with these photos), I got up close and personal with the new Airbus A380. I wasn’t that lucky to get inside, I think that was reserved for airline flight crews, but still there are a few photos.

I’ve had some media problems with both DVD’s containing photos of my Singapore/Thailand/Malaysia trip, but you can view a few Here on my Flickr.

Updated
7 Nov 2006 Airbus recently announced it’s third major delay, and today FedEx cancelled it’s order. Read more amount the details, and airline orders at Wikipedia.

On the features of Web 2.0 sites is the design pattern concept of The Perpetual Beta (See Point 6).

Seems Flickr or more likely Yahoo (the owner of Flickr) wants to be more.
Have a close look at the logo.

Google Earth and Google Maps can give you some great views of our planet. Here is a full-time blog just for Google Earth.

There’s plenty of amazing things to see, check out Top Ten Coolest Things seen with Google Earth. The list includes:

• Capsized Cruise Ship Captured in Google Earth / Maps
• KC-135 Caught Refueling C-5 Galaxy in Mid-Air in Google Earth!
• Huge Scale Model of Disputed Border Region of China Found in Google Earth
• Lancaster Bomber Caught Flying in Google Earth
• Flying Car? Not Really
• Nude Sunbather caught by google earth.
• Firefox Crop Circle in Google Earth
• Google Earth Las Vegas
• Shipwrecks Around the Google Earth
• See African Animals in High Resolution in Google Earth

Not to be outdone, check out the Google 3D Warehouse for images like Golden Gate Bridge.

Here are a few more cool things I’ve seen. Hole, More about the hole

I’ve heard of people that go plane spotting. Watching different planes that come into airports.

I’m lazy, while checking out my home with Wikimapia look what I spotted Here. (Offline image: View)

So for all those plane spotters. What is it? My guess would be an Boeing 737, probably a 737-800.

Speaking of Plane Spotting, I’ve been meaning of putting up my photos of the recent Asian Air Show in Singapore and my up close and personal photos of the Airbus A380.

Arrrrrgggggggggggghhhhhhhhhhhhhhhh! I’ve tried to retrieve my photos from DVD and I’m getting an cp: reading `/media/photos2006/photos/2006/2006_02_23_AirShow/IMG_5939.JPG’: Input/output error Error.

Well so much for those photos of Singapore, Bangkok and Malaysia from earlier in the year.
That’s gotta ruin your Sunday.

PS: How did I know what plane it was. Hint: the color gives it away.

PPS: Updated Jan 12 2007. Interesting that the present live view no longer has the plane. My Offline View has it. Good to know that this little area of Brisbane has been updated on Google Maps.

I guess much like the Slashdot effect, the Digg effect is both a good thing for your exposure and traffic hits, and a bad thing for those ISP’s watching the traffic. (See Jay’s Slashdot Fame).

In the past week, I’ve gone to a number of digg article sites and they have been unavailable. I never kept details of these IT articles, but here is one the one article not of an IT I look at that I did. It referred to an image, which the host provider adjusted (see image to the right). The host provider was ImageShack. I didn’t read anything in the T & C about being too popular!

Here’s the original Digg Post Gmail ads get a little too personal.

Seems I’m not the only person wanting to see it, I found in the comments a repost of the image Here. Just for future reference my copy is Here

PLUTO supporters from all over the world are burning things after the tiny cold planet was booted out of the solar system.

The decision caused uproar in the text book and hanging mobile industries, which will have to recall all their products and re-do them,

The disney company announced it would rename its famous cartoon dog.

Trivia questions, already at calamity points, will need to be rewritten and planetariums are busy papering over their Pluto exhibits, retraining guides and cutting the ends off posters.

From City News Issue 153 31 August 06

Following my User Group Presentation I was asked by fellow MySQLer Kim about Logical Data Modelling (LDM), in relation to Physical Data Modelling.

Well, first the brain had to work overtime to remember when was the last time I worked on a Logical Data Model. The answer to that is 1996 doing R&D work for Oracle Corporation with their CASE repository tool, Oracle Designer, about version 1.3/1.3.2. I’ve learnt in the past 10 years to purge technical stuff from my brain, leading from the capacity in be able to remember in detail data models, data migration and data cleansing issues of projects even after leaving them 3 years eariler.

As Kim pointed out, he thinks physically, actually directly at the SQL level, then working backwards to produce an appropiate physical model. To think logically is to consider the entities and attributes and relations before considering the physical tables, columns and relationships. So how do you program somebody to think logically? In the case with Kim, he is undertaking formal studies after already grasping the concepts of software development. Generally today more people don’t undertake the formal education and we end up with The Hobbist and the Professional Syndrome.

I guess in summary I’d argue why bother. Does anybody still do traditional logical models? Feedback/comments are welcome. (Professionally I believe there is a place for LDM).
However for the purpose of the exercise lets start with a Physical Representation and present a Logical Representation of that to see the differences.

From this you can see a classic Library example, showing a table of Books and a Table of Authors, and an intersection table (3NF) to indicate that a Book can have one to many Authors, and likewise an Author can have one to many Books.

So how would this have been represented in a Logical Model.

Some things to consider in Logical Modelling.

• Attributes really only require a name, and perhaps just a datatype using number, string, date (Jim Starkey would be happy), but nothing specific like SMALLINT, or VARCHAR(50).
• An Attributes Mandatory/Optional state may or may not be known
• Information is not in 3NF. i.e. relationships can be many to many (in our example, there is no concept of the intersection table

I’m going from memory here, so there is probably more points to consider.

So how do you teach this when you are trying to work backwards, when I learnt this back in 1988 (some 18 years ago), I’d never created a database or used SQL so I didn’t have the history. Arjen had a brilliant idea to consider Logical Modelling after the fact. Views. Consider an end user requirement for Reporting, and how you would represent your model better to an end user (effectively de-normalising these views so users don’t have to know about joins).

In this case you would create a view of Books and a View of Authors. Details such as mandatory/optional isn’t important to the end user report (ie, it’s not like it’s needed to be enforced), and specific datatype details again are not that important. The basics to know how to format a number or a date works.

An interesting approach that worked well in our explaining.

The Text Book

So it was interesting to go back to the text book using C.J. Date’s An Introduction to Database Systems to review definitions.

Logically isn’t really referenced, the term used is conceptual. A conceptual definition is “The right way to do database design is to get the logical design right first, without paying any attention whatsoever at that stage to physical - that is, performance - considerations”

Also for example Third Normal Form we get from Section 12.3 First, Second and Third Normal Forms.

Third normal form (very informal definition): A relvar is in 3NF if and only if the monkey attributes (if any) are both:

• a. Mutually independent
• b. Irreducibly dependent on the primary key

We explain the terms nonkey attribute and mutually independend (loosely) as follows:

• A nonkey attribute is any attribute that does not participate in the primary key of the relvar concerned.
• Two or more attributes are mutually independent if none of them is functionally dependent on any combination of the others. Such independence implies that each attributes can be updated independently of the rest.

Man, no wonder many years of experience and having generally seen most cases, enables me to forget this and not feel like I’ve fogotten something.

I first coined this term in February 2006 in a paper titled “Overcoming the Challenges of Establishing Service and Support Channels” for the conference “Implementing Open Source for Optimal Business Performance” View Paper.

I must have referenced this several times, time to give this topic it’s due notice. In summary it targets three areas:

• the lack of appropiate database design in open source projects
• the lack of coding standards
• the lack of sound programming principles

Here are the bullet points from the slide in a presentation.

Hobbist

• Downloadable software and examples
• Online tutorials
• Books like Learn in 24 hours/For Dummies

Professional

• Formal Qualifications
• Grounding in sound programming practices
• Understanding of SDLC principles
• Worked in team environment

Middle Ground Developer

• Time to skill verses output productivity
• Depends on environment and requirements

Well, now I have your attention, Slow Queries are bad (unless it’s a single user system and you don’t care). However there are worse things then slow queries in a large enterprise system.

I’ve been asked in recent weeks a number of questions which has brought this topic to discussion, as well as a current implementation I’m undertaking for a client of a purchased product.

High volume repetitive queries can have a worse effect on your system’s performance. Combined with slow queries that take locks, these queries can have an extreme effect on performance and if you don’t know your application, or have the right tools, it can be initially hard to diagonise easily.

This problem is the classic Wasting CPU cycles problem, seen it before, will see it again.

Here’s a classic example for reference. Using the current product that I’m customising and installing (I’ve not be involved in any development), a typical Customer Information System (CIS).

The system when deployed will have 1.1 Million Customers. Each Customer has a Balance. Now the Customer Balance is not recorded against the customer record, it’s calculated every time it’s required. So, no big deal, well yes. The stored procedure to calculate the balance hit’s 4 different tables, and one of these tables is one of the largest in the system (recording all detailed financial transactions). Multiple batch reports alone that work with large sets of customers all require or use the current balance in some means.

There are only a small set of transactions that affect the balance including Invoice Statements, Payments, Adjustments, Credit Control, Write-Offs . These processes by there own nature are either batch or small online transactions. The calculation of the balance can be applied against the Chunk of customers in a batch, or individual Row for online transactions (See The RAT and the CAT).

Even for the paranoid, the re-calculation of the customer balance for all customers in batch is more efficient after hours, yet only customers where some transaction that has been applied since the last time the re-calculation ran is necessary.

MySQL doesn’t be default have any analysis tools to identify and manage these types of queries. Peter Zaitsev in his article Slow Query Log analyzes tools highlights the issue with a good approach by a source code change to long_query_time as well as some additional scripts.

Hopefully MySQL will consider a more improved approach in future releases that doesn’t require patching the source code. Now it’s unlikely that MySQL will do another SHOW STATUS Gotcha and for example change the unit of measure from seconds to milliseconds, but they could make it a float, so you could specify 0.1 for example.

Want to know your Internet Connection speed in a real world test?
Want a fancy graphical presentation of your internet Speed?

SpeedTest.Net has you covered. As you can see that even provide graphics results to can use on your own site.

So just how much does my Bittorrent download of Stargate and StarGate Atlantis weekly epsiodes affect my link (Azureus states about 20kB/s down and 20kB/s up. Here is the results. Hmmm, seems if affects my link much more then it really states!

Sometimes using that Firefox Google Quick Search causes you to miss out on the best part of the Google Search experience, and that is the Google Doodle.

Now while I’m tempted to include one here, I’m respecting the wishes of Google which request you use an official logo and “don’t feed the kangaroo“.

So speaking of the Kangroo, you will need to goto the Google Doodle of the 2000 Summer Olympic Games held in Sydney Australia.

I’ve worked for two Internet startup companies, both around 2 years each, both now long dead. The first was due to eventual lack of new VC funds, the second gross financial managment in the second year (apparently, when we were told there was no money December one year to pay us, the company that made large profits every month for over the first year, then had made losses every month for the past 12 months, but nobody knew about it. There were 5 Directors from 3 countries and nobody knew. Yeah Right!)

I’ve learnt a lot of non IT street smarts in this time. The first startup took the VC route, and after 3 rounds while I wasn’t involved in the process you pick up things. The single biggest tip here is the Bell-Mason Diagnostic. Here a few introduction references worthy of a quick review (One, Two).

When you take any great idea, and then consider the 4 quadrants and 12 axis you realise you really need to make larger circles of professional contacts.

Zac’s article Valley Boys Run MySQL talks about the new breed of Web entrepreneurs and Web 2.0. In particular check out
Valley Boys Digg.com’s Kevin Rose leads a new brat pack of young entrepreneurs. This is the new wave of success that works without VC.

For me this recent post on the Meebo Blog really impressed me.

365 days ago

Nineteen releases, eleven (fantastic) team members, and 295,321 gummy bears later we see over a million users log into meebo each day. As a coder, all you hope is that your service will be able help people go about their day-to-day lives. Stability, bugs, and good usability are always top of mind.

1,000,000 users of your Web 2.0 application. This impresses and motivates me. What makes it possible to anybody, is you can get a LAMP stack, a live-cd, cheap hosting and you can turn your idea into something real for next to no cost. Of course, I won’t start on the nightmares out there of great ideas that are very poorly designed. At least the underlying stack can support anything you want to achieve, and MySQL is behind these success stories.

One more thing on Meebo, Check out the meebo map!. I’ve been told that Google has something of a similar nature at the Googleplex. Well I can say I’m very keen to see this, and will be 8 weeks time when the First MySQL Camp is held.

Sheeri talked a little about MySQL Triggers in One TRIGGER Fact, Optimizer Rewriting Stuff. While it’s great that MySQL 5.0 has Triggers, there are some things that I feel could become features in future releases.

IF EXISTS

One of the beautiful features that MySQL has is IF EXISTS. This ternary operation that if the object exists performs the operation, of not it does nothing works wonders in reviewing logs for errors. One of the problems with Oracle for example, is the requirement to ignore the ORA errors for non-existent objects.

But this functionality doesn’t exist for Triggers? One must wonder why. I’d like to see this.

mysql> DROP TRIGGER IF EXISTS trigger_name;

MySQL Manual DROP TRIGGER

REPLACE

On feature that simplifies the lack of IF EXISTS functionality using Oracle is REPLACE. The syntax is:

oracle> CREATE OR REPLACE TRIGGER trigger_name...

In this case, this functionality effectively eliminates the need for a DROP IF EXISTS, however I’d not like to see this introduced into MySQL especially it’s an Oracle specific syntax and not ANSI SQL.

Multiple Triggers of same type per table

MySQL only allows one Trigger per type per table. That is, there can only be one BEFORE UPDATE for example. While you may ask the question why you would need this functionality. Here is a typical situation.

You use Triggers to perform some level of business functionality, determining values for optimised (denormalised) columns is a good example. So you need to write an appropiate trigger for that piece of functionality.
You also use Triggers to perform database auditing, that is for every insert/update/delete of data, you record a full copy of the change in an audit database. One way to ensure this is consistent across the entire database is to implement via triggers. So you leverage programming functionality to pre-create triggers for all tables to manage this.

The problem with MySQL occurs in that you have to now merge these triggers for tables that require both. If you want to deploy your application into a test environment, you may wish to not deploy your auditing triggers, but now you have this functionality mixed in with business logic.

Multi Type Triggers

Another cool Oracle feature is the capacity to define a trigger for multiple types. For example:

oracle> CREATE OR REPLACE TRIGGER trigger_name
oracle> BEFORE INSERT OR DELETE OR UPDATE ON table_name ...

In this example, with MySQL you would need to create three seperate triggers.

Other features

While not as important and one would need to consider if necessary in MySQL are some other Oracle provided trigger functionality. This includes:

• WHEN CLAUSE trigger restriction
• Triggers on DDL Statements such as CREATE, DROP, ALTER
• Triggers on Database events such as LOGON, LOGOFF, STARTUP, and SHUTDOWN
• INSTEAD OF Triggers (for Views)
• STATEMENT based trigger

For more information you can check out the Oracle Documentation on Introduction to Triggers, CREATE TRIGGER, Documentation Search on Triggers