This blog post was inspired by my visit at the annual Zabbix Conference in Riga, Latvia this year, where I gave a couple of talks on MySQL and beyond.

It was a two day single-track event with some 200 participants, a number of interesting talks on Zabbix (and related technologies) and really well-organized evening activities. I was amazed how well organized the event was and hope to be invited to speak there next year as well.   (Just in case you’re not sure what Zabbix is, it is an enterprise-class open source distributed monitoring solution for networks and applications)

I must secretly confess, it was also the first conference …

Did your logging stop working after you set up logrotate? Then this post might be for you.

Archive your log files!

Some time ago, Peter Boros wrote about Rotating MySQL Slow Logs safely, explaining the steps of a “best practice” log rotate/archive. This post will add more info about the topic.

When running logrotate for MySQL (after proper setting the /etc/logrotate.d/mysql conf file) from anacron, there’s a situation that you might potentially face if the user and password used to execute the “flush logs” command is stored in, for example, /root/.my.cnf file.

The situation:

You might find out that you have a new MySQL log file ready to receive data, but nothing is being written to it.

Why did this happen?

The logrotate script is executed, but the postrotate …

MySQL database usage is popular in OpenStack. Core OpenStack services for Compute (Nova), Storage (Cinder), Neutron (Networking), Image (Glance) and Identity (Keystone) all use MySQL database.

MySQL – as the world’s most popular database, runs inside OpenStack Virtual Machines and serves as database backend to OpenStack cloud based applications. The MySQL instances can be configured to run in virtual machines manually (by simply installing MySQL inside a VM and running it) or can be created in an on-demand fashion by OpenStack Database-as-a-Service (Trove).

In either case, the MySQL data is mission-critical. OpenStack cloud administrators and cloud guests/tenants need the ability to backup and restore their MySQL databases. mysqldump is traditional way of doing MySQL backups and restores. However, based on previous experiences of the MySQL community, it is widely known that mysqldump has …

A deadlock in MySQL happens when two or more transactions mutually hold and request for locks, creating a cycle of dependencies. In a transaction system, deadlocks are a fact of life and not completely avoidable. InnoDB automatically detects transaction deadlocks, rollbacks a transaction immediately and returns an error. It uses a metric to pick the easiest transaction to rollback. Though an occasional deadlock is not something to worry about, frequent occurrences call for attention.

Before MySQL 5.6, only the latest deadlock can be reviewed using SHOW ENGINE INNODB STATUS command. But with Percona Toolkit’s pt-deadlock-logger you can have deadlock information retrieved from SHOW ENGINE INNODB STATUS at a given interval and saved to a file or table for late diagnosis. For more information on using pt-deadlock-logger, see …

In many write-intensive workloads Innodb/XtraDB storage engines you may see hidden and dangerous “debt” being accumulated – unpurged transaction “history” which if not kept in check over time will cause serve performance regression or will take all free space and cause an outage. Let’s talk about where it comes from and what can you do to avoid running into the trouble.

Technical Background: InnoDB is an MVCC engine which means it keeps multiple versions of the rows in the database, and when rows are deleted or updated they are not immediately removed from the database but kept for some time – until they can be removed. For a majority of OLTP workloads they can be removed seconds after the change actually took place. In some cases though they might need to be kept for a long period of time – if there are some old transactions running in the system that might still need to look at an old database state. As of …

MySQL has information_schema.tables that contain information such as “data_length” or “avg_row_length.” Documentation on this table however is quite poor, making an assumption that those fields are self explanatory – they are not when it comes to tables that employ compression. And this is where inconsistency is born. Lets take a look at the same table containing some highly compressible data using different storage engines that support MySQL compression:

TokuDB:

mysql> select * from information_schema.tables where table_schema='test' G
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: test
TABLE_NAME: comp
TABLE_TYPE: BASE TABLE
ENGINE: TokuDB
VERSION: 10
ROW_FORMAT: tokudb_zlib
TABLE_ROWS: 40960
AVG_ROW_LENGTH: 10003
DATA_LENGTH: 409722880
MAX_DATA_LENGTH: …

Recently I encountered a specific situation in which a customer was forced to stay with the MyISAM engine due to a legacy application using tables with over 1000 columns. Unfortunately InnoDB has a limit at this point. I did not expect to hear this argument for MyISAM. It is usually about full text search or spatial indexes functionality that were missing in InnoDB, and which were introduced in MySQL 5.6 and 5.7, respectively, to let people forget about MyISAM. In this case though, InnoDB still could not be used, so I gave the TokuDB a try.

I’ve created a simple bash script to generate a SQL file with …

Percona Server and Percona XtraDB Cluster provide high-performance alternatives for MySQL users. We have also seen rapidly growing interest in these solutions in the OpenStack community where higher performance and high availability are crucial. Many OpenStack users are adopting these solutions but we’ve also seen demand from companies creating OpenStack distros. For example, Percona XtraDB Cluster is now certified for the RHEL OSP (OpenStack Platform) and is included in the Ubuntu 14.04 LTS release. …

MySQL upgrades are necessary tasks and we field a variety of questions here at Percona Support regarding MySQL upgrade best practices. This post highlights recommended ways to upgrade MySQL in different scenarios.

Why are MySQL upgrades needed? The reasons are many and include: Access to new features, performance benefits, bug fixes…. However, MySQL upgrades can be risky if not tested extensively beforehand with your application because the process might break it, prevent the application from functioning properly – or performance issues could arise following the upgrade. Moreover, I suggest keeping an eye on new releases of MySQL and Percona Server – check what has changed in the …

Percona is glad to announce the release of Percona Server 5.6.20-68.0 on August 29, 2014. Download the latest version from the Percona web site or from the Percona Software Repositories.

Based on MySQL 5.6.20, including all the bug fixes in it, Percona Server 5.6.20-68.0 is the current GA release in the Percona Server 5.6 series. All of Percona’s software is open-source and …