This is an issue that keeps rearing its ugly head over and over again, and since it greatly affects performance, it is most important that DBAs of any DMBS running on Linux come to grips with it. So I decided to do some research and try different settings on my notebook. Here are my findings.

What can you find on the web?

A Wikipedia search for the word swappiness will come up empty (any volunteers out there want to write an article?). A Google search will show some pretty old material—the best article I found is from 2004: Linux: Tuning Swappiness. This article includes a detailed discussion with some interesting remarks by Andrew Morton, a Linux kernel maintainer.

So, what is swappiness?

Towards the end of the email thread quoted in the article, you’ll find this definition (sort of):

> I’ve read the source for where …

Welcome to the 142nd edition of Log Buffer, the weekly review of database blogs.

The SQL Server ’sphere was a busy place this week. On In Recovery… Paul S. Randall posted his latest straw poll, this time looking into your practices around transaction log size management.

Linchi Shea observed, “In a multi-process/multi-thread system, locking is central to maintain data consistency and keep things in order.  . . . [We] need to begin with understanding the locking behavior of the basic building blocks offered by SQL Server . . .  [One] would think that the basic locking behavior …

I’m excited to announce that Paul Vallée, Pythian Founder and Executive Chairman, will be on-the-air online this week with a free webinar — Database Platform Migration: when is it strategically appropriate to migrate existing applications to an open-source platform? It’s based on our 10+ years experience supporting proprietary databases, such as Oracle and SQL Server, and open-source MySQL databases on the other hand and what we learned on the numerous migrations.

One of the recent projects completed with one of our Australian clients — 1 TB Oracle RDB on OpenVMS migrated to MySQL on Linux with Heartbeat cluster for high availability.

On the other hand, one telco client in Sydney, which we provide Oracle support for, notified me that they recently migrated a MySQL database to Oracle because they couldn’t find high quality enterprise level support for it. I wish we were engaged with them earlier but they seem to be …

In December 2007 Werner Vogels posted a blog article entitled Eventual Consistency, since updated with a new article entitled Eventually Consistent - Revisited. In a nutshell it described how to scale databases horizontally across nodes by systematically trading off availability, strict data consistency, and partition resilience as defined by the CAP theorem. According to CAP, you can only have two of three of these properties at any one time. The route to highly available and performant databases, according to Vogels, is eventual consistency in which distributed database contents at some point converge to a single value but at any given time may be …

Welcome to the 141st edition of Log Buffer, the weekly review of database blogs. The Oracle bloggers were especially chatty this week, so let’s start with them.

Rob van Wijk wrote a fine post about choosing between SQL and PL/SQL, defending his choice of straight-up SQL for logic. Naturally, this triggered a lot of discussion, as well as a few responses from other blogs. Chen Shapira framed her response in a question about code life-cycle: would you rather maintain SQL or PL/SQL?

H. Tonguç …

I am passing this along — I am not sure if most folks reading this can make it, as it is last-minute and in the Boston area, but I figured I’d let people know that the New England Database Society exists. It’s free, sponsored by Sun (and has been for years, long before Sun bought MySQL), and is hosted by my college database professor, Mitch Cherniack. (To that end, I should probably make sure to promote the Boston User Group here more often! I keep forgetting…)

You can find information on how to be a part of the mailing list at http://www.cs.brown.edu/sites/neds/

The next New England Database Society will be held on Friday, March 27 and the speaker is Christian Jensen of Aalborg University.

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[N]ew [E]ngland [D]atabase …

I mentioned in my previous post that recently I have been working with web performance. Often when working with clients they want fast performing web sites but then proceed to give you all manner of other requirements which slow the site down to a crawl. Convincing a client to give you the time to look at performance isn't easy, while the gains in speed are there for all to see attributing some monetary value to that is close to impossible. In the longer term you might see an up turn in the traffic levels or a higher percentage of people taking a longer user journey on your site but whether that was a result of higher performance is very difficult to prove.

Thankfully one of our larger clients could see the benefit of having a dedicated resource looking at performance issues, all be it as a result of such poor performance that the sites became difficult to use during peek times. When a client keeps throwing stuff at you it's easy to …

Here are some quotes from a recent article talking about Oracle's maintenance and support fees:

Before Oracle acquired BEA earlier this year, the company charged 18% to 20% for support and maintenance. Oracle increased those fees to meet its own structure and also raised list prices on most BEA products.

That didn't sit well.

and


One Java-centric VAR, who spoke on the condition of anonymity, said some of his BEA WebLogic customers are moving to alternative application servers just to get away from Oracle.

and

"What company comes in this climate and not only jacks up prices but support prices as …

Here are some quotes from a recent article talking about Oracle's maintenance and support fees:

Before Oracle acquired BEA earlier this year, the company charged 18% to 20% for support and maintenance. Oracle increased those fees to meet its own structure and also raised list prices on most BEA products.

That didn't sit well.

and


One Java-centric VAR, who spoke on the condition of anonymity, said some of his BEA WebLogic customers are moving to alternative application servers just to get away from Oracle.

and

"What company comes in this climate and not only jacks up prices but support prices as …

Here are some quotes from a recent article talking about Oracle's maintenance and support fees:

Before Oracle acquired BEA earlier this year, the company charged 18% to 20% for support and maintenance. Oracle increased those fees to meet its own structure and also raised list prices on most BEA products.

That didn't sit well.

and


One Java-centric VAR, who spoke on the condition of anonymity, said some of his BEA WebLogic customers are moving to alternative application servers just to get away from Oracle.

and

"What company comes in this climate and not only jacks up prices but support prices as …