August 29, 2014

Virident vCache vs. FlashCache: Part 1

(This is part one of a two part series) Over the past few weeks I have been looking at a preview release of Virident’s vCache software, which is a kernel module and set of utilities designed to provide functionality similar to that of FlashCache. In particular, Virident engaged Percona to do a usability and feature-set […]

Disconnecting a replication slave is easier with MySQL 5.5+ (RESET SLAVE vs. RESET SLAVE ALL)

It’s not uncommon to promote a server from slave to master. One of the key things to protect your data integrity is to make sure that the promoted slave is permanently disconnected from its old master. If not, it may get writes from the old master, which can cause all kinds of data corruption. MySQL […]

Innodb vs MySQL index counts

I had a customer recently who a few strange errors in their mysqld.err log:

This customer was running Percona Server 5.1 and they got this error on two tables during a maintenance window when they were adding indexes to the same tables.  We had a suspicion that it had something to do with Fast […]

PHP vs. BIGINT vs. float conversion caveat

Sometimes you need to work with big numbers in PHP (gulp). For example, sometimes 32-bit identifiers are not enough and you have to use BIGINT 64-bit ids; e.g. if you are encoding additional information like the server ID into high bits of the ID. I had already written about the mess that 64-bit integers are […]

Fixing column encoding mess in MySQL

Just had an interesting issue with an encoding mess on a column containing non-ASCII (Russian) text. The solution was not immediately obvious so I decided it’s worth sharing. The column (actually the whole table) was created with DEFAULT CHARSET cp1251. Most of the data was in proper cp1251 national encoding indeed. However, because of web […]

Test Drive of Solid

Not so long ago Solid released solidDB for MySQL Beta 3 so I decided now is time to take a bit closer look on new transactional engine for MySQL. While my far goal is the performance and scalability testing before I wanted to look at basic transactional properties such as deadlock detection, select for update […]

Why TokuDB hates Transparent HugePages

If you try to install the TokuDB storage engine on a modern Linux distribution it might fail with following error message: 2014-07-17 19:02:55 13865 [ERROR] TokuDB will not run with transparent huge pages enabled. 2014-07-17 19:02:55 13865 [ERROR] Please disable them to continue. 2014-07-17 19:02:55 13865 [ERROR] (echo never > /sys/kernel/mm/transparent_hugepage/enabled) You might be curious […]

Percona XtraDB Cluster 5.6.19-25.6 is now available

Percona is glad to announce the new release of Percona XtraDB Cluster 5.6 on July 21st 2014. Binaries are available from downloads area or from our software repositories. We’re also happy to announce that Ubuntu 14.04 LTS users can now download, install, and upgrade Percona XtraDB Cluster 5.6 from Percona’s software repositories. Based on Percona […]

Failover with the MySQL Utilities – Part 1: mysqlrpladmin

MySQL Utilities are a set of tools provided by Oracle to perform many kinds of administrative tasks. When GTID-replication is enabled, 2 tools can be used for slave promotion: mysqlrpladmin and mysqlfailover. We will review mysqlrpladmin (version 1.4.3) in this post. Summary mysqlrpladmin can perform manual failover/switchover when GTID-replication is enabled. You need to have […]

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 […]