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Category Archives: Web/Tech

“High Performance MySQL” by Baron Schwartz, Peter Zaitsev, and Vadim Tkachenko; O’Reilly Media

Peter and Vadim are long-term contributors to MySQL open source code base and are the founders of Percona, MySQL consultancy. This is really THE book about MySQL written by engineers who have spent more than a decade working on MySQL code. The book is equally valuable to devops and DB admins, as well as software […]

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Measuring user retention using cohort analysis with R

Cohort analysis is super important if you want to know if your service is in fact a leaky bucket despite nice growth of absolute numbers. There’s a good write up on that subject “Cohorts, Retention, Churn, ARPU” by Matt Johnson. So how to do it using R and how to visualize it. Inspired by examples […]

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Book review: Programming Amazon EC2

Should you buy a book on a new technology or just read technology provider’s guidelines, instructions and recommendations? This book was released over a year ago, so naturally it doesn’t cover all the latest developments that happened on Amazon AWS platform. For example Simple Email Service (SES) and Dynamo DB are not mentioned at all. After […]

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Setting up and securing web server (+MySQL +Rails/PHP) on Ubuntu 10.04 LTS

After repeating these operations many times in various setups, I decided to create a public set of instructions and share them with the world. This should be suitable for most of the simple web sites, utilizing Ruby on Rails or PHP. The setup works on Ubuntu 10.04 Server LTS (scheduled end of life April 2015). Other […]

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Informal notes from Strata 2012 conference on Big Data and Data Science

It’s been almost a month since I came back from California, and I just got around to sorting the notes from O’Reilly Strata conference. Spending time in the Valley is always inspiring – lots of interesting people, old friends, new contacts, new start-ups – it is the center of IT universe. Spending 3 days with […]

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Notes from Gothenburg – Nordic Ruby 2011 conference

Here are my notes from Nordic Ruby conference in Göteborg, Sweden. I’d like to say big thanks to the organisers of the conference (especially CJ @cjkihlbom) – everything went really smooth, even though there’s been 150 people attending this year compared to 90 last year. Some points that I’d really like to highlight are: a […]

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vim is the best editor, also for RoR development

vim is a natural choice when you’re starting a new programming project (if you’re emacs or textmate adept – you can stop reading now If you’re starting a Ruby on Rails project there are a couple of scripts/configurations you might want to install to make development with vim an even more pleasant experience. 1. Rails.vim […]

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Increasing Ruby interpreter performance by adjusting garbage collector settings

According to Evan Weaver from Twitter it is possible for a typical production Rails app on Ruby 1.8 to recover 20% to 40% of user CPU by simply adjusting Ruby garbage collector settings. In August I set out on a quest to verify that statement on HeiaHeia servers. Results have really exceeded my expectations. Time to […]

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Call to undefined function: imagecreatefromjpeg()

While installing new Joomla modules I came across this PHP error (yep, still have to deal with PHP occasionally). I had PHP compiled from source on Ubuntu 10.04 as per earlier instructions. Quick check of phpinfo() indicated that while gd module was compiled in, it didn’t have JPEG support: GD Support enabled GD Version bundled […]

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Running Rails applications using Nginx with Passenger on Ubuntu Server

If you’re planning to run Rails applications on Nginx using Phusion Passenger, and do it on Ubuntu Linux, here’s what needs to be done. Even though there’s Ubuntu nginx package available (which works perfectly when you’re running PHP apps using FCGI), if you want to take into use Phusion Passenger, you’ll need to recompile Nginx […]

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