This past week I attended OSCon, the annual conference for open source’s true believers. And there was a religious fervor in the air, particularly from the point of view of someone more accustomed to Oracle conferences.

And if open source is the religion, proprietary closed-source companies are the devil. That having been said, I was surprised how virtually all large companies were demonized. Even long-time defenders of open source like IBM were ignored at best. That didn’t prevent them from coming though, with Microsoft and HP in particular with high-profile sponsorships and PR offensives that didn’t seem to have much influence with the crowd.

The companies generating buzz were the small companies built around development of their own open source products. There are a surprising number of them out there, especially relating to multiple forks of a popular product like MySQL or …

A couple students in one of my classes ran into a problem when competing Java threads tried to insert new rows in a table. They raised an error when they tried the DELAY keyword to avoid the race (collision) condition in an INSERT statement. It was simple to explain to them that the DELAY keyword doesn’t work with an InnoDB table. Any attempt throws the following error:

      ERROR 1616 (HY000): DELAYED OPTION NOT supported FOR TABLE 'message'

Important Update: INSERT DELAYED is gone in MySQL 5.6.6 (announcement) and the whole issue comes down to synchronizing threads (some dislike the solution) or using the ON DUPLICATE KEY …

Converting from uw-mailboxes (mbx) to Unix format (dovecot)

It took me by surprise how the mailbox formats had changed, when I switched to Dovecot which is the best IMAP/POP3 mail program, in my opinion. It handles large (enormous) mailboxes with many (hundreds of) users. Caching makes things go fast again.

Here is a simple bash utility, to take all users, and convert all mailboxes & folders.

cd /home
for u in *
do
if [ -d /home/$u/Mail ]; then
echo "User: $u"
cd /home/$u/Mail

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On Linux, you have a plethora of File Systems available.

Recently I was testing databases (MySQL, MariaDB) especially with ThreadPool against a Violin Flash Memory Array, and I forgot what file system the LUN was mounted (and formatted) as.

There are two ways to find out:

• df -T (show mounted life systems, along with the FS type)
• file -s /dev/xxx (show more details about a FS node)

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I’m leaving myself some room for bug fixes. It works for us in house. I would love to help others to give it a try. especially those who could benefit from making nearly immediately answered queries to the NIST’s NVD database.

The code in this release cannot by itself track the feed from the feds in real time. The nvd entry loader needs a little bit of love in the area of record merging before this starts working. It’s on my TODO list.

I’m sorry for the outage of git.colliertech.org. I’ll get that back up here shortly. In the meantime, feel free to grab it from this location while the CPAN indexes and processes my submission.

http://www.colliertech.org/federal/NIST/NIST-NVD-1.00.00.tar.bz2

don’t forget to check the cryptographic signature:

…

A new company often means new responsibilities and learning new ways of doing things. For a tech guy, it often means picking up a new framework or maybe if you are a glutton for punishment, a new language. I recently switched OSes, languages, and databases as a DBA/DB Developer. This was quite a massive shift for me. I went from the stable, enterprise database, SQL Server, to the little engine that could, MySQL. Before the switch, I would stew over the fact that SQL Server lacked features in comparison to Oracle or Postgres, but now I realize that there are far better things to worry about (such as non-blocking backups). I just wanted to go over some of the differences I found.

1. MySQL is a collection of binaries that manipulate data files. It is not a monolithic application that persists its data to disk, but instead it allows another process to manipulate its files even while it’s running. It interprets a folder in its data directory …

I learned how to use a computer on DOS and Windows. My first programming projects were written in QBASIC and my first Web applications were written in VB using ASP on Windows 2000. The first job where I made decent money was developing a SQL Server-based application. I bought my first car, an engagement ring, and a honeymoon with money from making software on Windows. Needless to say, I found a lot of intellectual and financial fulfillment from Windows over the years.

That first real job also allowed me flexibility in what technology I could employ, and I helped implement a features using Redis on top of Ubuntu. This was a fun time, because my company basically paid me to study a new technology and to gain experience using it. On my own, I began to use Linux and to embrace open-source ideas, one of which is that the consumer is also the producer. I changed my mindset about what it means to use software: for open-source projects, it often …

With the rapid advancement in the database technologies, the legacy systems are either being upgraded or they are being replaced or in some cases technologists are finding ways to support them in new ways showing us the flexible nature of databases and the belief of professionals that the sky is the limit. For this Log [...]

Retrouvez SkySQL et ses partenaires sur le stand C21 du Salon Solutions Linux 2012 au CNIT à Paris du 19 au 21 juin

Cette année, le Salon Solutions Linux à Paris coincide avec la Fête de la Musique. C’est donc avec enthousiasme que nous nous préparons pour cet évènement annuel incontournable dédié aux logiciels libres et à l’Open Source.

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Do the operating systems kill your MySQL instances from time to time? Are some database servers swapping constantly? These are relatively common problems. Why? How to prevent them?

Memory allocation

When a running program needs some additional memory, it can typically allocate it dynamically with malloc() function. It finds an unused continuous block that is at least as large as the requested size, reserves as much as it needs, and returns a pointer to that space. No initialization of the memory contents is performed at the time. When malloc() returns NULL instead of a valid address, it is an information to the calling program that there wasn’t enough memory available and the call has failed to allocate anything. In such cases applications typically take appropriate actions to notify users about the problem and terminate some of their activity or completely shut down.

In Linux it can be a little bit …