November 21, 2014

How to deal with MySQL deadlocks

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 […]

Trawling the binlog with FlexCDC and new FlexCDC plugins for MySQL

Swanhart-Tools includes FlexCDC, a change data capture tool for MySQL. FlexCDC follows a server’s binary log and usually writes “changelogs” that track the changes to tables in the database. I say usually because the latest version of Swanhart-Tools (only in github for now) supports FlexCDC plugins, which allow you to send the updates to a remote […]

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 […]

Check for MySQL slave lag with Percona Toolkit plugin for Tungsten Replicator

A while back, I made some changes to the plugin interface for pt-online-schema-change which allows custom replication checks to be written. As I was adding this functionality, I also added the –plugin option to pt-table-checksum. This was released in Percona Toolkit 2.2.8. With these additions, I spent some time writing a plugin that allows Percona […]

Getting to know TokuDB for MySQL

During last April’s Percona Live MySQL Conference and Expo, TokuDB celebrated it’s first full-year as an open source storage engine. I still remember reading the official announcement and the expectations it created one year ago. The premises were very interesting as it had the potential of helping MySQL manage “big data” in a way InnoDB just […]

Using InfiniDB MySQL server with Hadoop cluster for data analytics

In my previous post about Hadoop and Impala I benchmarked performance of analytical queries in Impala. This time I’ve tried InfiniDB for Hadoop (open-source version) on the modern hardware with an 8-node Hadoop cluster. One of the main advantages (at least for me) of InifiniDB for Hadoop is that it stores the data inside the Hadoop cluster but uses the […]

Q&A: Common (but deadly) MySQL Development Mistakes

On Wednesday I gave a presentation on “How to Avoid Common (but Deadly) MySQL Development 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 had time […]

Oracle’s Morgan Tocker opens up about MySQL development, MySQL 5.7

Today’s post features an interview with Morgan Tocker, MySQL community manager at Oracle. Morgan is an old friend of Percona, having worked here as director of MySQL training from 2009 to 2011. He’s also done stints at MySQL, Sun Microsystems and InPowered. You can follow his adventures at his blog, “Master MySQL.”  You can also […]

Multiple column index vs multiple indexes with MySQL 5.6

A question often comes when talking about indexing: should we use multiple column indexes or multiple indexes on single columns? Peter Zaitsev wrote about it back in 2008 and the conclusion then was that a multiple column index is most often the best solution. But with all the recent optimizer improvements, is there anything different with […]

Renaming database schema in MySQL

One of the routine tasks for a DBA is renaming database schemas, and as such MySQL added a command to carry out that purpose called “RENAME DATABASE <database_name>”. However this command just made it through a few minor releases before being discontinued (from MySQL 5.1.7 to 5.1.23). Here’s a link to the reference manual regarding […]