MySQL

nginx and WordPress

Reuven M. Lerner — Tue, 08 Nov 2016 12:13:35 +0000

In my last article, I took an initial look at nginx, the high-performance open-source HTTP that uses a single process and a single thread to service a large number of requests. nginx was designed for speed and scalability, as opposed to Apache, which was designed to maximize flexibility and configuration. But through the years, nginx has become increasingly flexible as well, with a growing number of plugins and modules that can be used to customize its configuration. Between the performance, increasingly good documentation and convenience, it's no wonder nginx has been increasingly popular.

It's also no surprise that WordPress, the open-source blogging and CMS platform, has become hugely popular. I've heard people say that 10% of websites are now run using WordPress. Even if that's not precisely true, there's no doubt that a huge number of sites are powered by WordPress. I'm a mostly satisfied WordPress user, having converted my main site and my two ebook sites to it in the past year after years of using it to power my blog.

So, I thought it would be interesting to demonstrate how easy it is to set up WordPress with nginx, given the popularity of each of these systems alone as well as together. In my last article, I described how you can set up a plain-vanilla PHP system with nginx; WordPress is a bit more complex, but less than you might think. Starting with a bare-bones Linux installation, let's walk through the configuration needed to get WordPress up and running.

The Basics

In order to install WordPress and nginx together, you're going to need three basic software systems installed: WordPress, nginx and MySQL. The first two are pretty obvious, given this article's goal; the third is a byproduct of using WordPress, which works exclusively with MySQL.

So, on my Ubuntu Linux machine, I would run the following:


$ sudo apt-get install mysql-server mysql-client nginx-core
 ↪php5-cli php5-fpm php5-mysql

This installs a very large number of packages, but it will give you the core of what you need to get your system up and running. Notice that you're not installing WordPress here, so that you can install it manually, using the source code. Indeed, installing WordPress via apt-get also means installing Apache; although it's certainly possible to undo this choice, the benefits of installing WordPress on your own outweigh those of doing it via a package manager.

You will, as part of this installation, need to choose a password for your MySQL root user. This is an important part of security on your system, so do try to use a strong password.

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Tune Up Your Databases!

Shawn Powers — Thu, 03 Mar 2016 18:54:57 +0000

by Shawn Powers

My last full-time job was manager of a university's database department. Ironically, I know very, very little about databases themselves. I'm no longer in charge of college databases, but I still do have a handful of MySQL servers that run my various Web applications. Apart from apt-get install, I have no idea how to make databases work. Thankfully, help is available.

MySQLTuner is a Perl script that checks your local (or remote) MySQL server and gives recommendations for improving security and performance. It does not edit files or actually make changes to the server, but it does give a very lengthy list of recommendations. If you (like me) are the sort of person who just tends to copy/paste database setup instructions, running MySQLTuner is a really good idea.

You can download your copy at http://mysqltuner.com. Be sure to read the documentation to get the most use out of the program. And, if you discover security problems like the ones shown in my screenshot? Fix them!

Thanks to its ability to help improve and secure MySQL servers that otherwise might be vulnerable, MySQLTuner gets this month's Editors' Choice award. If you're imperfect like me, download a copy today and fine-tune your databases!

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MySQL—Some Handy Know-How

Shawn Powers — Wed, 30 Dec 2015 19:29:56 +0000

by Shawn Powers

I recently was talking to someone over IRC who was helping me with a PHP app that was giving me trouble. The extremely helpful individual asked me to let him know the value of a certain field in a record on my MySQL server. I embarrassingly admitted that I'd have to install something like PHPMyAdmin or Adminer in order to find that information. He was very gracious and sent me a simple one-liner I could run on the command line to get the information he needed. I was very thankful, but admittedly embarrassed. I figured if I don't know how to get simple information from a MySQL server, there probably are others in the same boat. So, let's learn a little SQL together.

Get a Database

It turns out there are quite a few sample databases to download from the Internet. Unfortunately, they're all far more complicated than I'd like to use for demonstration purposes. So, I created a database. Although you don't have to have my database in order to follow along, it certainly will help if you do. So first, let's create a database and import my data.

The first thing you need to do is install MySQL. Depending on your distribution, this either will be an apt-get command, a yum command, or a search in the GUI software center. I'll leave the installation to you—feel free to use Google if you're struggling. The main thing is to remember the root password you set during the installation process. This isn't the same as the root password for your system; rather it's the root user in your MySQL server. If you're using a live server, just create a new user/password with access to create databases. I'm going to assume you've just installed MySQL, and you know the root user's password.

When you work with MySQL on the command line, you use the "mysql" application. So in order to create the database for this example, type:


mysql -u root -p -e "CREATE DATABASE food"

You should be prompted for a password, which is the password you set during installation for the MySQL root user account. If you get an error about the database already existing, you can choose a new name for your database. Just realize that the name you pick will be what you'll use later when I refer to the "food" database.

Next, you need to get my data into your database. I have an SQL file stored at http://snar.co/foodsql. You can download that file, or use wget on the command line to get it. If you use wget, the resulting filename might be "foodsql" or "food.sql", depending on how your version of wget works. Either filename will work, just make note of what you have so you can change the command you're going to use below. To download and import the data, type:

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Using MySQL for Load Balancing and Job Control under Slurm

Steven Buczkowski — Mon, 19 Oct 2015 18:39:35 +0000

by Steven Buczkowski

Like most things these days, modern atmospheric science is all about big data. Whether it's an instrument flying in an aircraft taking sets of images several times a second and producing three quarters of a terabyte of data per flight day over a two-week campaign or a satellite instrument producing hundreds of gigs of spectral data daily over a 10–15 year lifetime, data volume is enormous. Simply analyzing a day's worth of data to keep track of basic instrument stability is CPU-intensive. Fully processing a day to retrieve the state of the atmosphere or looking at trends across a decade's worth of data is exponentially so.

High-performance parallel cluster computing is the name of the game. For years I've done this on a very basic level by kicking off a handful of copies of my processing scripts on a couple computers around the lab, but after a recent move into a new lab, I got my first chance to work on a real cluster system, processing data from a satellite-borne hyperspectral sounder called AIRS (see Resources). AIRS is one of the instruments onboard NASA's AQUA satellite that was launched in late 2002 and has been in continuous operation since. Data from AIRS and similar instruments is used to map out vertical profiles of atmospheric temperature and trace gases globally, but we have to be able to process it first.

The cluster computing game here is strictly to get a whole lot of computers doing the same thing to a whole lot of data so that we can process it faster than we collect it (much faster would be preferable). Since I was new to this game just a few months ago, I've had much to learn about cluster computing and how to design algorithms and processing software to take advantage of multiple CPUs for processing. This was my first experience where I had hundreds of CPUs at my disposal, and it really has changed how I process data in general. I started this article to describe how I was shown to parallelize this type of data processing and a method I put together that makes the process much cleaner.

Basic Slurm

The cluster system here consists of 240 compute nodes, each with dual, 8-core processors and 64GB of main memory running Red Hat Enterprise Linux. Cluster jobs are scheduled to run through the Slurm workload manager (see Resources). In a nutshell, Slurm is a suite of programs that works to allocate computer resources among users and compute jobs and enforce sharing rules to make sure everyone gets a chance to get their work in. The two most important programs in the suite for actually working on the system are sbatch and srun.

sbatch is the entry point to the Slurm scheduler and reads a high-level Bash control script that specifies job parameters (number of nodes needed, memory per process, expected run times and so on) and spawns the requested number of identical jobs via calls to srun.

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Moving Databases

Shawn Powers — Mon, 15 Aug 2011 13:00:00 +0000

by Shawn Powers

I recently moved my personal website from GoDaddy to my home server. I have a business connection at my house, and my site gets little enough traffic that hosting at home on my static IP makes sense. Moving the files wasn't really difficult, I FTP'd them down from the old server, and SFTP'd them up to the new server. Moving the database was a bit more challenging, however.

If you have shell access, it's a pretty simple process. On the old server, type:

mysqldump -u username -p databasename > databasebackup.sql

You'll be asked for the password assigned to "username", and then mysqldump will create a file that contains all the information needed to restore your database. One thing to note, however, is that going between different versions of mysql can be problematic. That's where the --compatible flag is handy. You can specify what type of database software you'll be importing to, and mysqldump will (try) to give you a compatible file. Some options are mysql323, postgresql, mysql40, etc. Check the man page for more options and explanations about what they all do.

To restore your database file on the new server, it's just as easy. Simply type:

mysql -u username -p newdatabasename < databasebackup.sql

That should transfer your data simply and easily. If you get errors, you might have to check that --compatible flag, or even do some more work to your database in order to make it compatible. One of the frustrating things with GoDaddy, however, is that you don't get shell access to your hosting account. Since my account was disabled, any mysql tools that might be available via their website were also unavailable. That's why it's important to have some backup software running regularly on your website. I was able to take an automated backup from a week ago, and simply import it into my new server.

The moral of the story, like most, is that backups are VERY important! It's great to know the tools to make a dump of your mysql database, but if something is corrupt, you'll want a backup rather than a fresh dump. If you have any other tips for moving databases from one server to another, feel free to leave them in the comments.

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