October 24, 2014

Monitoring MySQL flow control in Percona XtraDB Cluster 5.6

Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and wsrep_flow_control_paused_ns. Which one should you use? What is flow control? Flow control does not exist with regular MySQL replication, […]

Percona XtraDB Cluster: Setting up a simple cluster

Percona XtraDB Cluster (PXC) is different enough from async replication that it can be a bit of a puzzle how to do things the Galera way.  This post will attempt to illustrate the basics of setting up 2 node PXC cluster from scratch. Requirements Two servers (could be VMs) that can talk to each other. […]

Galera Flow Control in Percona XtraDB Cluster for MySQL

Last week at Percona Live, I delivered a six-hour tutorial about Percona XtraDB Cluster (PXC) for MySQL.  I actually had more material than I covered (by design), but one thing I regret we didn’t cover was Flow control.  So, I thought I’d write a post covering flow control because it is important to understand. What […]

Using flow control functions for performance monitoring queries

I’m not big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to create queries which are poorly readable as well as can hardly be optimized well by MySQL Optimizer. One way I find IF statement very useful is computing multiple aggregates over different set […]

‘Bash Bug’ giving you Shellshock? CVE-2014-6271 update

The media train is in full steam today over the the CVE-2014-6271 programming flaw, better known as the “Bash Bug” or “Shellshock” – the original problem was disclosed on Wednesday via this post. Firstly this issue exploits bash environment variables in order to execute arbitrary commands; a simple check for this per the Red Hat […]

Galera replication – how to recover a PXC cluster

Galera replication for MySQL brings not only the new, great features to our ecosystem, but also introduces completely new maintenance techniques. Are you concerned about adding such new complexity to your MySQL environment? Perhaps that concern is unnecessarily. I am going to present here some simple tips that hopefully will let fresh Galera users prevent […]

OpenStack’s Trove: The benefits of this database as a service (DBaaS)

In a previous post, my colleague Dimitri Vanoverbeke discussed at a high level the concepts of database as a service (DBaaS), OpenStack and OpenStack’s implementation of a DBaaS, Trove. Today I’d like to delve a bit further into Trove and discuss where it fits in, and who benefits. Just to recap, Trove is OpenStack’s implementation […]

Getting my hands dirty on an OpenStack lab

Like you all may know, OpenStack is currently one of the coolest open source projects, so I was thrilled when I was asked to manage the deployment of an OpenStack lab for internal Percona use. Starting from basically zero, I created tasks in our Jira and assigned them to a pool of volunteer consultants. As usual in […]

A schema change inconsistency with Galera Cluster for MySQL

I recently worked on a case where one node of a Galera cluster had its schema desynchronized with the other nodes. And that was although Total Order Isolation method was in effect to perform the schema changes. Let’s see what happened. Background For those of you who are not familiar with how Galera can perform […]

Managing shards of MySQL databases with MySQL Fabric

This is the fourth post in our MySQL Fabric series. In case you’re joining us now, we started with an introductory post, and then discussed High Availability (HA) using MySQL Fabric here (Part 1) and here (Part 2). Today we will talk about how MySQL Fabric can help you scale out MySQL databases with sharding. Introduction At the […]