September 16, 2014

High-availability options for MySQL, October 2013 update

The technologies allowing to build highly-available (HA) MySQL solutions are in constant evolution and they cover very different needs and use cases. In order to help people choose the best HA solution for their needs, we decided, Jay Janssen and I, to publish, on a regular basis (hopefully, this is the first), an update on […]

Another reason why SQL_SLAVE_SKIP_COUNTER is bad in MySQL

It is everywhere in the world of MySQL that if your replication is broken because an event caused a duplicate key or a row was not found and it cannot be updated or deleted, then you can use ‘ STOP SLAVE; SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE; ‘ and be done with it. In some cases this is fine and you can repair the […]

Schema changes – what’s new in MySQL 5.6?

Among many of the improvements you can enjoy in MySQL 5.6, there is one that addresses a huge operational problem that most DBAs and System Administrators encounter in their life: schema changes. While it is usually not a problem for small tables or those in early stages of product life cycle, schema changes become a […]

Common MySQL traps webinar questions followup

Thanks to all attendees of the webinar yesterday! If you missed it, you can watch the video recording. Here are some questions that remained unanswered due to time constraints. Q: Are there any technical considerations or best practice tips to have a replicated slave in the cloud, for example on Amazon AWS? Hardware resources are […]

MySQL Upgrade Webinar Questions Followup

I did a Webinar about MySQL Upgrade – Best Practices Yesterday and there were some questions we could not answer during Webinar, following Jay’s Lead I decided to post them as a Blog Post. Q: Can you go directly MySQL 5.0 to 5.5 for MyISAM tables? MyISAM have not been getting any significant development since […]

read_buffer_size can break your replication

There are some variables that can affect the replication behavior and sometimes cause some big troubles. In this post I’m going to talk about read_buffer_size and how this variable together with max_allowed_packet can break your replication. The setup is a master-master replication with the following values: max_allowed_packet = 32M read_buffer_size = 100M To break the […]

Product to try: MySQL/MariaDB-Galera 0.8

I wrote about Galera about 1.5 years ago: State of the art: Galera – synchronous replication for InnoDB. It was about the 0.7 release, which was more like a proof-of-concept release (though Galera’s developers may not agree with that ) with some serious limitations (like using mysqldump for node propagation). The Galera team heard my […]

Ultimate MySQL variable and status reference list

I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just as frequently, I want to look up blog posts on variables, or look for content in the Percona documentation or forums. So I present to you what is now my newest Firefox toolbar bookmark: an option and […]

MySQL Limitations Part 3: Subqueries

This is the third in a series on what’s seriously limiting MySQL in certain circumstances (links: part 1, 2). This post is about subqueries, which in some cases execute outside-in instead of inside-out as users expect.

MySQL Limitations Part 1: Single-Threaded Replication

I recently mentioned a few of the big “non-starter” limitations Postgres has overcome for specific use cases. I decided to write a series of blog posts on MySQL’s unsolved severe limitations. I mean limitations that really hobble it for major, important needs — not in areas where it isn’t used, but in areas where it […]