August 30, 2014

mysqld_multi: How to run multiple instances of MySQL

The need to have multiple instances of MySQL (the well-known mysqld process) running in the same server concurrently in a transparent way, instead of having them executed in separate containers/virtual machines, is not very common. Yet from time to time the Percona Support team receives a request from a customer to assist in the configuration of […]

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 […]

High Availability with mysqlnd_ms on Percona XtraDB Cluster

This is the second part of my series on High Availability with mysqlnd_ms. In my first post, “Simple MySQL Master HA with mysqlnd_ms,” I showed a simple HA solution using asynchronous MySQL replication. This time we will see how to leverage an all-primary cluster where you can write to all nodes. In this post I used […]

Simple MySQL Master HA with mysqlnd_ms

I had the pleasure of presenting to the PHP Users Group Philippines a few days ago about mysqlnd_ms. The mysqlnd plugin, MySQL Master Slave, is a transparent layer on top of mysqlnd extension. This allows you to do read-write splitting and slave reads load balancing without needing to change anything from your application. But do […]

Using MySQL 5.6 Performance Schema in multi-tenant environments

Hosting a shared MySQL instance for your internal or external clients (“multi-tenant”) was always a challenge. Multi-tenants approach or a “schema-per-customer” approach is pretty common nowadays to host multiple clients on the same MySQL sever. One of issues of this approach, however, is the lack of visibility: it is hard to tell how many resources (queries, disk, […]

Errant transactions: Major hurdle for GTID-based failover in MySQL 5.6

I have previously written about the new replication protocol that comes with GTIDs in MySQL 5.6. Because of this new replication protocol, you can inadvertently create errant transactions that may turn any failover to a nightmare. Let’s see the problems and the potential solutions. In short Errant transactions may cause all kinds of data corruption/replication […]

MySQL Audit Plugin now available in Percona Server 5.5 and 5.6

The new Percona Server 5.5.37-35.0 and Percona Server 5.6.17-65.0-56, announced yesterday (May 6), both include the open source version of the MySQL Audit Plugin. The MySQL Audit Plugin is used to log all queries or connections (“audit” MySQL usage). Until yesterday’s release, the MySQL Audit Plugin was only available in MySQL Enterprise. EDIT:  Just to be clear, this implementation […]

How to identify and cure MySQL replication slave lag

Here on the Percona MySQL Support team, we often see issues where a customer is complaining about replication delays – and many times the problem ends up being tied to MySQL replication slave lag. This of course is nothing new for MySQL users and we’ve had a few posts here on the MySQL Performance Blog […]

How to find bugs in MySQL

Finding bugs in MySQL is not only fun, it’s also something I have been doing the last four years of my life. Whether you want to become the next Shane Bester (who is generally considered the most skilled MySQL bug hunter worldwide), or just want to prove you can outsmart some of the world’s best […]

MySQL server memory usage troubleshooting tips

There are many blog posts already written on topics related to “MySQL server memory usage,” but nevertheless there are some who still get confused when troubleshooting issues associated with memory usage for MySQL. As a Percona support engineer, I’m seeing many issues regularly related to heavy server loads – OR OOM killer got invoked and […]