This article goes along similar lines to the piece I did on the security of MySQL. I came across another blog that asked about programming tips that really should not be followed in the real world. I thought it might be interesting to get some ideas of what areas of MySQL or database theory that is taught as "religion" at University or even in starting positions that just don't work in the real world in some situations.

I will get the ball rolling by adding a few points that are often drummed into people, but don't work in all situations.

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Thanks to Google and MySQL I have been given an opportunity to create a project from scratch with the help of a mentor, but it is fundamentally different that projects given at school. Unless you are in a software engineering course projects are generally given out with about two weeks to complete them and they are not prerequisites for the next project. The design process is severely diminished in that situation because the time constraint forces a more programming centric approach to complete the program. Not to say that design should take a majority of the time over coding, but I have found that for my project it is not only time saving, but essential to completing the project with the goals I have set. I will briefly explain how the design process has positively influenced my project.

Object Oriented Design is Complicated

The key to the success of my project will be its modularity; how simple could someone add a …

Sometimes it´s useful to take a look at the querylog, when you see a growing graph in a monitoring tool and think "what´s happening there?"
But there is no need to keep it always enabled as it produces I/O load.
To enable the querylog, the mysqld must be restartet, which means downtime and this is not acceptable. So I found the following way:

• start the mysqld with querylog enabled
• delete the querylog file and keep the mysqld running
• issue a "flush logs" when you need the querylog. The mysqld re-creates the file and you can look at it.
• remove the querylog file when finished

Ok, not the perfect way, but it seems to work. But don´t forget the side effects of a "flush logs". This command creates a new binlog and errorlog too.

It’s been a long time since I bought a book about mysql, so I thought I would ask what were some of the recent good books around about mysql.

The only good book I know is ‘high performance mysql’, but it is from 2004. so I’m concerned it’s a bit dated.

So.. what’s on your bookshelves?

In the mid-90s, at the very starting edge of the dotcom boom, I was the lead tech guy behind a project, we put a nationwide yellow pages database on the web, ypol.com.

At the time, nobody else had done it, but we were sure that many other people had had the same idea. And since it's rare for someone to care about finding a plumber or locksmith in another state in the middle of the night, of course I had location based searches from the start.

It was, in fact, my first real encounter with using Oracle, Sybase, and using Perl to interface to a DB. (This was before Perl5, so there was no DBI module, so it was all oraperl.)


It looks like someone has actually patented the idea of location based searches on a online yellow pages database, has put together an investor-based lawsuit machine, and has fired the first salvo by suing Verizon.

I'm pretty damn sure my old YPOL project is prior …

Yesterday I was asked for help concerning a replication problem with one of our test systems. My colleague had already installed a fresh dump he had created with mysqldump ... --master-data. The dump looked ok and contained a master configuration statement:

...
CHANGE MASTER TO MASTER_LOG_FILE='master-bin.000127',MASTER_LOG_POS=4462223;
...

The slave was provided with the correct user, password and host name for this master. Nevertheless issuing a START SLAVE did not work. In the slave .err file we found this:

 
...
050327 20:54:51 [ERROR] Error reading packet from server: Client requested master to start replication from impossible position (server_errno=1236)
050327 20:54:51 [ERROR] Got fatal error 1236: 'Client requested master to start replication from impossible position' from master when reading data from binary log
...

After some fiddling around and searching the net for …

Yesterday I was asked for help concerning a replication problem with one of our test systems. My colleague had already installed a fresh dump he had created with mysqldump ... --master-data. The dump looked ok and contained a master configuration statement:

...
CHANGE MASTER TO MASTER_LOG_FILE='master-bin.000127',MASTER_LOG_POS=4462223;
...

The slave was provided with the correct user, password and host name for this master. Nevertheless issuing a START SLAVE did not work. In the slave .err file we found this:

 
...
050327 20:54:51 [ERROR] Error reading packet from server: Client requested master to start replication from impossible position (server_errno=1236)
050327 20:54:51 [ERROR] Got fatal error 1236: 'Client requested master to start replication from impossible position' from master when reading data from binary log
...

After some fiddling around and searching the net for …

MySQL Connector/Net 5.1.2 a new version of the all-managed .NET driver for MySQL has been released.

Connector/Net 5.1 represents a change in how we package our products. Until now, we've shipped our core provider and the Visual Studio integration bits as separate downloads. This has become a bit of a problem. Often we would fix a bug that involved changing code both in the VS package and in the core provider. This provided a versioning problem where users would need to upgrade both products to see the benefit of the bug fix. To solve this, we've decided to discontinue Tools for Visual Studio as a separate product and have, instead, integrated it into a new Connector/Net installer. We hope this provides a better "out of box" experience for our users.

All previous versions of Tools for Visual Studio should be uninstalled prior to installing this product.

Version 5.1.2 works with all versions of MySQL …

OverviewTest suites are hard, but your business needs to have one.
They are hard because modern applications are complex.
Technology can help you. There are tools that can simplify the task of creating a thorough test suite.

Does your main business have a regression test?The likely answers to the above questions are:

• Yes. - Good chap. Keep up the good work. You may stop reading, but just out of curiosity, read on.
  
• No. I don't need one. - You may stop reading. Most likely your business is already doomed. :)
• No. I don't have time (don't know how) to make one. - Keep reading. There is something for you.

What's a regression test? Is a useful watchdog that tells you if your software is working the way it was intended to.
If you don't have one, you have no quick and reliable …

Wow! It has really been 4 months since my last post?? Moving over to development has cut into the time I had for blogging, documenting, communicating, you name it! We are coding like crazy.

Well, I'm back because I am heading out to ODTUG Kaleidoscope next week, and in preparation for the show, I decided to setup Pentaho on Oracle's Java Edition App Server, which is OC4J, which is based on the Orion app server. I was pleased that I managed the migration in less than a day, and I wanted to share the steps with all those folks who are too impatient to wait for this to get into our J2EE deployment distribution :)

Mind you, it takes a bit of tweaking, but it is certainly very do-able, and all server features are stable (minus the portal stuff, I didn't get a chance to address moving the portal over). Here is the repro of where I started, what I …