November 26, 2014

Using Apache Hadoop and Impala together with MySQL for data analysis

Apache Hadoop is commonly used for data analysis. It is fast for data loads and scalable. In a previous post I showed how to integrate MySQL with Hadoop. In this post I will show how to export a table from  MySQL to Hadoop, load the data to Cloudera Impala (columnar format) and run a reporting […]

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 5.5 and MySQL 5.6 default variable values differences

As the part of analyzing surprising MySQL 5.5 vs MySQL 5.6 performance results I’ve been looking at changes to default variable values. To do that I’ve loaded the values from MySQL 5.5.30 and MySQL 5.6.10 to the different tables and ran the query:

Lets go over to see what are the most important changes […]

The relationship between Innodb Log checkpointing and dirty Buffer pool pages

This is a time-honored topic, and there’s no shortage of articles on the topic on this blog. I wanted to write a post trying to condense and clarify those posts, as it has taken me a while to really understand this relationship. Some basic facts Most of us know that writing into Innodb updates buffer […]

Recovering Linux software RAID, RAID5 Array

Dealing with MySQL you might need to deal with RAID recovery every so often. Sometimes because of client lacking the proper backup or sometimes because recovering RAID might improve recovery, for example you might get point in time recovery while backup setup only takes you to the point where last binary log was backed up. […]

Beware: ext3 and sync-binlog do not play well together

One of our customers reported strange problem with MySQL having extremely poor performance when sync-binlog=1 is enabled, even though the system with RAID and BBU were expected to have much better performance. The problem could be repeated with SysBench as follows:

Where to get recent MySQL version ?

As you might noticed there are no recent MySQL Community versions available for download from MySQL Download Area This applies both to binaries (which is expected with new polices) but also to the source files which were promised to be available. So what is if you would like to use recent MySQL code while staying […]

Percona Server 5.5.32-31.0 now available

Percona is glad to announce the release of Percona Server 5.5.32-31.0 on July 2nd, 2013 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.5.32, including all the bug fixes in it, Percona Server 5.5.32-31.0 is now the current stable release in the 5.5 series. All of Percona‘s software is open-source and free, all the details of the release […]

The write cache: Swap insanity tome III

Swapping has always been something bad for MySQL performance but it is even more important for HA systems. It is so important to avoid swapping with HA that NDB cluster basically forbids calling malloc after the startup phase and hence its rather complex configuration. Probably most readers of this blog know (or should know) about […]

Pacemaker, please meet NDB Cluster or using Pacemaker/Heartbeat to start a NDB Cluster

Customers have always asked me to make NDB Cluster starts automatically upon startup of the servers. For the ones who know NDB Cluster, it is tricky to make it starts automatically. I know at least 2 sets of scripts to manage NDB startup, ndb-initializer and from Johan configurator www.severalnines.com. If all the nodes come up […]