Queries in MySQL, Sphinx and many other database or search engines are typically single-threaded. That is when you issue a single query on your brand new r910 with 32 CPU cores and 16 disks, the maximum that is going to be used to process this query at any given point is 1 CPU core and [...]
Announcing Percona Server 5.1.66-14.2
Percona is glad to announce the release of Percona Server 5.1.66-14.2 on January 15th, 2013 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.1.66, including all the bug fixes in it, Percona Server 5.1.66-14.2 is now the current stable release in the 5.1 series. All of Percona‘s software is open-source and free, all the details of the release can [...]
Sphinx search performance optimization: attribute-based filters
One of the most common causes of a poor Sphinx search performance I find our customers face is misuse of search filters. In this article I will cover how Sphinx attributes (which are normally used for filtering) work, when they are a good idea to use and what to do when they are not, but [...]
Profiling MySQL Memory Usage With Valgrind Massif
There are times where you need to know exactly how much memory the mysqld server (or any other program) is using, where (i.e. for what function) it was allocated, how it got there (a backtrace, please!), and at what point in time the allocation happened. For example; you may have noticed a sharp memory increase [...]
How does MySQL Replication really work?
While we do have many blog posts on replication on our blog, such as on replication being single-threaded, on semi-synchronous replication or on estimating replication capacity, I don’t think we have one that covers the very basics of how MySQL replication really works on the high level. Or it’s been so long ago I can’t [...]
Announcing Percona Server 5.5.28-29.3
Percona is glad to announce the release of Percona Server 5.5.28-29.3 on January 8th, 2012 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.5.28, including all the bug fixes in it, Percona Server 5.5.28-29.3 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 can [...]
Percona Toolkit Webinar followup Q&A
First, a thank you to everyone who attended the webinar Today, I appreciate your time and nice comments. As promised, here are answers to questions that couldn’t be answered during the talk: Q: How do you install the tools? The manual has full details, but it’s important to know that the latest release for [...]
Full table scan vs full index scan performance
Earlier this week, Cédric blogged about how easy we can get confused between a covering index and a full index scan in the EXPLAIN output. While a covering index (seen with EXPLAIN as Extra: Using index) is a very interesting performance optimization, a full index scan (type: index) is according to the documentation the 2nd [...]
Replaying database load with Percona Playback
If you are planning to upgrade or make any configuration change on your MySQL database the first advice usually is: – Benchmark! How should we do that benchmark? People usually run generic benchmark tools like sysbench, tpcc or mysqlslap that are good to know the number of transactions per seconds that a database can do [...]
Review of MySQL 5.6 Defaults Changes
James Day just posted the great summary of defaults changes in MySQL 5.6 compared to MySQL 5.5 In general there are a lot of good changes and many defaults are now computed instead of hardcoded. Though some of changes are rather puzzling for me. Lets go over them: back_log = 50 + ( max_connections / [...]

