This is yet another story of Django web-framework with time zone support and pain dealing with python datetimes and MySQL on the backend. In other words, offset-naive vs offset-aware datetimes.

Shortly, more about the problem. After reading the official documentation about the time zones, it makes clear that in order to reflect python datetime in the necessary time zone you need to make it tz-aware first and than show in that time zone.

Here is the first issue: tz-aware in what time zone? MySQL stores timestamps in UTC and converts for storage/retrieval from/to the current time zone. By default, the current time zone is the server’s time, can be changed on MySQL globally, per connection etc. So it becomes not obvious what was tz of the value initially before stored in UTC. If you …

Twitter is not my favorite social media site. Using twitter is like driving downtown, screaming what you want to say out the window, and hoping someone hears you. There might be tens of thousands of people downtown, but your message will only be heard by a few. Your best bet is to repeat your message as often as possible.

However, twitter is free and if you want to reach as many people (theoretically) as possible, you might as well use it. But sending tweets on a scheduled basis can be a pain. There are client programs available which allow you to schedule your tweets (Hootsuite is one I have used in the past). You can load your tweets in the morning, and have the application tweet for you all day long. But you still have to load the application with your tweets – one by one.

A friend of mine asked me if there was a way to send the same 200 tweets over and over again, spaced out every 20 minutes or so. He has a consulting …

This is a follow-up post to my recent announcement of only_full_group_by improvements in 5.7, where I’d like to address some tricky corner cases where GROUP BY contains non-column expressions (functions).

In the SQL standard, GROUP BY should contain only table columns and never expressions. So this example query where we want to count how many people have the same name is illegal in the SQL2011 standard because the GROUP BY clause contains a function:

CREATE TABLE people (first_name VARCHAR(100), last_name VARCHAR(100));

SELECT CONCAT(first_name, ' ', last_name), COUNT(*)
FROM people
GROUP BY CONCAT(first_name, ' ', last_name);

But MySQL does allow expressions in a GROUP BY clause, and it’s a very convenient addition to the standard. The logic …

We want you to learn as much as possible during the three days of conference. We do that through quality and variety of both content and speakers, as well as creating a fun and friendly atmosphere.

We have presentations for any level, from beginner to advanced. You’ll learn about the backend and frontend, web and mobile, information systems and games, hard and soft skills, as well as many related topics.

We have speakers from many different countries and industries. They brings unique perspectives that you won’t find in your backyard. How often will you talk tech with someone from Taiwan or Saudi Arabia? How often will you learn from people who build robots or write their own programming language?

If your goal is to learn and meet interesting people, then ConFoo is the conference for you! Take advantage of our $190 early bird …

Imagine that two colleagues, Alice and Bob, issue a command to launch a new virtual machine at approximately the same moment in time. Both Alice’s and Bob’s virtual machines must be given an IP address within the range of IP addresses granted to their project. Let’s say that range is 192.168.20.0/28, which would allow for a total of 16 IP addresses for virtual machines [1]. At some point during the launch sequence of these instances, Nova must assign one of those addresses to each virtual machine.

How do we prevent Nova from assigning the same IP address to both virtual machines?

In this blog post, I’ll try to answer the above question and shed some light on issues that have come to light about the way in which OpenStack projects currently solve (and sometimes fail) to address this issue.

Demonstrating the …

I'm starting off 2015 with the following New Year's Resolution, to improve the state of benchmarking. About a month ago I noticed the following tweet:
Hey @tokutek, please look at this: http://stssoft.com/products/stsdb-4-0/benchmark …. Are the benchmarks rigged or correctly done? I'm curious to know! While I've never met Ian Campbell (@iamic) he certainly knew how to call me to action. I immediately checked out the STSsoft website, the benchmark results page, and the benchmark code itself. My first reaction …

We have been using SHOW ENGINE INNODB MUTEX command for years. It shows us mutex and rw-lock information that could be useful during service troubleshooting in case of performance problems. As Morgan Tocker announced in his blog post the command will be removed from MySQL 5.7 and we have to use performance_schema to get that info.

The documentation of MySQL also says that most of the command output has been removed from 5.6 and that we can find similar info in performance_schema. It doesn’t show any examples of how to use performance_schema or what is the query we need to use from now on. It is also important to mention that 5.6 doesn’t show any warning about the feature being deprecated.

This is a short blog post to show how to configure performance_schema and get the info we need. Hoping it will end …

In this blog post I will describe different ways of using SSL with the MySQL database server.

What does SSL give you?

You might use MySQL replication over the internet or connect to MySQL over the internet.

Another posibility is that you connect over an enterprise network to which just too many people have access. This is especially an issue if you use an BYOD network.

SSL helps here by encrypting the network traffic to prevent against evesdropping. It also validates that you're talking to the correct server to prevent man-in-the-middle attacks.

And you can also use SSL client certificates together with an password as two factor authentication.

SSL is not the only option, you could use SSH and many MySQL GUI clients like MySQL Workbench support …

Sometimes it is desired to use particular software versions in production, and not necessary the latest ones. There may be several reasons for that, where I think the most common is when a new version should spend some time in testing or a staging environment before getting to production. In theory each new version is supposed to be better as usually it contains a handful of bug fixes and even new or improved functionality. However there is also a risk of some regression or a new bug introduction as a side effect of code changes.

Quite often DBAs want the same MySQL version to be installed on all database instances, regardless of what actually is the latest version available in the software provider’s repository. There are several ways to achieve this:
* download specific version packages manually and then install them,
* have custom local repository mirror where you decide when and which version gets there, and just update …

January 5, 2015 By Severalnines

Cloud storage is hot. Dropbox, Apple iCloud, Google Drive, Microsoft SkyDrive and Amazon Cloud Drive all offer cloud sharing platforms where you can store documents in the cloud and access them from all your devices. For enterprises who require full control, ownCloud is an open source solution that allows files to be stored on-premises and/or a backend cloud. 

In this blog post, we’ll show you how to deploy a high availability setup using ownCloud Community Edition. We will need to set up redundancy in each of the following layers:

• file storage
• web server
• database server
• load balancer

We will use five servers. ownCloud will run on three separate servers with MySQL Galera Cluster 5.6 and GlusterFS running on RHEL 6.5 64bit. ownCloud supports GlusterFS as primary storage. ClusterControl will be co-located …