While doing some testing (that I published later here) on the still-in-development MySQL 5.7 I wanted to do some analysis on the configuration to see if the changes in performance were due to the code changes or just to the new MySQL defaults (something that is very common in the migration from 5.5 to 5.6 due to the default transaction log size and other InnoDB parameters). This is a quick post aiming to identify the global variables changed between these two versions.

You could tell me that you could just read the release notes, but my experience (and this is not an exception, as you will see) …

We've all heard the hype.  MySQL 5.6 is packed with amazing new features that address all our database problems.  5.6 deals with replication and HA and performance and monitoring and security and features.  It just may cure cancer.

In fact it's been out for ages.  It went GA  …

A bit of history

The latest version of Red Hat Enterprise Linux, one of the most popular and respected Linux distributions in the server market, was released in June 2014, followed by CentOS 7 and Oracle Linux releases in July of the same year.

There are very interesting changes for database administrators in these new releases, among which I would like to highlight the fact that installer now chooses XFS as its filesystem by default, which substitutes ext4 as the preferred format for local data storage. Red …

This comes from an issue that I worked on recently, wherein a customer reported that their application was working fine under stock MySQL 5.6 but producing erroneous results when they tried running it on Amazon RDS 5.6. They had a table which, on the working server, contained two TIMESTAMP columns, one which defaulted to CURRENT_TIMESTAMP and the other which defaulted to ’0000-00-00 00:00:00′, like so:

CREATE TABLE mysql56 (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  ts1 TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  ts2 TIMESTAMP NOT NULL DEFAULT '0000-00-00 00:00:00',
);

However, under Amazon RDS, the same table looked like this:

CREATE TABLE rds56 ( 
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  ts1 TIMESTAMP NULL DEFAULT NULL,
  ts2 TIMESTAMP NULL DEFAULT NULL, 
);

They mentioned that their schema contains TIMESTAMP column definitions without any modifiers for nullability or …

MySQL, the original brand, the one developed by the MySQL team at Oracle, is steadily evolving. You can feel it if you try every new release that comes out of the milestone release cycle. Or even if you don’t try all of them, just testing a release once in a while gives you something to think about.

The engineers at Oracle are trying hard to improve the defaults. If you are the out-of-the-box type, and just install the new version on top of the previous one, leaving the same setup in place, you may be up for a for a few surprises. It’s the marketing, see? They tell you that just by replacing your old MySQL (5.1 or 5.5) with MySQL 5.6 you get 30% to 70% performance improvement. Which happens to be true, not only because the server is better, but also because they have changed the defaults. However, this change in defaults may come with some serious consequences for the ones who …

A colleague and I have been looking at GTID on MySQL recently and you may be interested in the blog post that results from that. You can see it here. http://blog.booking.com/mysql-5.6-gtids-evaluation-and-online-migration.html.

MySQL 5.6 has been GA for just over a year now. See MySQL 5.6.10 Release Notes.  Congratulations on your birthday! That is quite a long time. I was using it earlier in production because it worked and could do things that 5.5 could not do, but earlier versions were to use at your own risk, and indeed if prodded incorrectly would fall on the floor. That is fair enough because they were work in progress, yet if you poked them the right way they did a very good job.  Those dev versions have been long since upgraded which is good so they do not need quite as much care and attention.

So from where I see 5.6 it works very well. One big change that has made a large difference but which I think a lot of people may not really understand or use is the …

 At Facebook, we have upgraded most of MySQL database tiers to 5.6, except very few tiers that have a special requirement -- very fast single threaded replication speed.

 As Oli mentioned, single threaded performance is worse in 5.6. The regression is actually not visible in most cases. For remote clients, the performance regression is almost negligible because network latency is longer than 5.1->5.6 overhead. If clients are running locally but MySQL server is disk i/o bound, the overhead is negligible too because disk i/o latency is much longer than 5.1->5.6 overhead.

 But the regression is obvious when clients run locally and queries are CPU bound. The most well known local client program for MySQL is SQL Thread (Replication Thread). Yes, 5.6 has a slower replication performance problem, if SQL thread is …

I was really pleased to see the announcement by Oracle MySQL yum repositories that they have now produced a yum repository from where the MySQL RPMs they provide can be downloaded. This makes keeping up to date much easier. Many companies setup internal yum repositories with the software they need as then updating servers is much easier and can be done with a simple command. For many people at home that means you set this up once and don’t need to check for updates and do manual downloads, but can do a quick yum update xxxx and you get the latest version. Great!  This new yum repository only covers RHEL6 did not include RHEL5 which is not yet end of life and still used by me and probably quite a lot of other people. I filed bug#70773 to ask for RHEL5 support to be …

A few years ago Yves Trudeau and Aleksandr Kuzminsky wrote posts about different ways for recovering orphaned .ibd files:

• Connecting orphaned .ibd files
• A recovery trivia or how to recover from a lost ibdata1 file

Today I want to show you how to do that in more easy and quick way. In my example I’ll restore a “payment.ibd” file (payment table) from Sakila DB on a server with MySQL 5.5 (but with …