November 28, 2014

MySQL Error: Too many connections

We have always received quite few questions here at Percona Support on how to avoid the dreaded “Too many connections” error, as well as what is the recommended value for max_connections. So, in this article I will try to cover best possible answers to these questions so others can mitigate similar kinds of issues. My […]

Innotop: A real-time, advanced investigation tool for MySQL

GUI monitoring tools for MySQL are not always suitable for all our needs or situations. Most of them are designed to provide historical views into what happens to our database over time rather then real-time insight into current MySQL server status. Excellent free tools for this include Cacti, Zabbix, Ganglia, Nagios, etc. But each of […]

Impact of the number of idle connections in MySQL

Be careful with my findings, I appear to have compile in debug mode, I am redoing the benchmarks. Updated version here. I recently had to work with many customers having large number of connections opened in MySQL and although I told them this was not optimal, I had no solid arguments to present. More than […]

Are PHP persistent connections evil ?

As you probably know PHP “mysql” extension supported persistent connections but they were disabled in new “mysqli” extension, which is probably one of the reasons some people delay migration to this extension. The reason behind using persistent connections is of course reducing number of connects which are rather expensive, even though they are much faster […]

Avoiding MySQL ALTER table downtime

MySQL table alterations can interrupt production traffic causing bad customer experience or in worst cases, loss of revenue. Not all DBAs, developers, syadmins know MySQL well enough to avoid this pitfall. DBAs usually encounter these kinds of production interruptions when working with upgrade scripts that touch both application and database or if an inexperienced admin/dev […]

Percona XtraDB Cluster 5.5.39-25.11 is now available

Percona is glad to announce the new release of Percona XtraDB Cluster 5.5 on September 5th 2014. Binaries are available from downloads area or from our software repositories. Based on Percona Server 5.5.39-36.0 including all the bug fixes in it, Galera Replicator 2.11, and on Codership wsrep API 25.11, Percona XtraDB Cluster 5.5.39-25.11 is now […]

Heartbleed: Separating FAQ From FUD

If you’ve been following this blog (my colleague, David Busby, posted about it yesterday) or any tech news outlet in the past few days, you’ve probably seen some mention of the “Heartbleed” vulnerability in certain versions of the OpenSSL library. So what is ‘Heartbleed’, really? In short, Heartbleed is an information-leak issue. An attacker can […]

Introducing backup locks in Percona Server

TL;DR version: The backup locks feature introduced in Percona Server 5.6.16-64.0 is a lightweight alternative to FLUSH TABLES WITH READ LOCK and can be used to take both physical and logical backups with less downtime on busy servers. To employ the feature with mysqldump, use mysqldump –lock-for-backup –single-transaction. The next release of Percona XtraBackup will […]

8 common (but deadly) MySQL operations mistakes and how to avoid them

January 22 I gave a presentation on “How to Avoid Common (but Deadly) MySQL Operations Mistakes” for Percona MySQL Webinars. If you missed it, you can still register to view the recording and my slides. Thanks to everyone who attended, and especially to folks who asked the great questions. I answered as many as we […]

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 […]