May 24, 2013

Is MySQL 5.6 slower than MySQL 5.5?

February 18, 2013 By 23 Comments

There have been a number reports/benchmarks showing MySQL 5.6 to be slower than MySQL 5.5 on variety of workloads. There are many possible reasons and I believe we will learn about many of them in the next few weeks and months as MySQL 5.6 is starting to get production battle-tested and there is inflow of [...]

Filed Under: MySQL Tagged With: , , ,

Sphinx search performance optimization: multi-threaded search

January 16, 2013 By 6 Comments

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 [...]

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CVE-2012-4414 strikes back in MySQL 5.5.29 (and what we’re doing in Percona Server 5.5.29)

January 13, 2013 By 4 Comments

In preparing Percona Server 5.5.29 (not yet released, but soon), I filed MySQL bug 68045 (is marked private as it’s a security bug). This bug is in relation to the Oracle fix for CVE-2012-4414 and a problem I found with it. The MariaDB fix (which we incorporated into Percona Server 5.5.28-29.3) is not affected. When the [...]

Filed Under: MySQL, Percona Software Tagged With: , ,

Profiling MySQL Memory Usage With Valgrind Massif

January 9, 2013 By 1 Comment

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 [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL, Quality Assurance

Concatenating MyISAM files

November 19, 2012 By 5 Comments

Recently, I found myself involved in the migration of a large read-only InnoDB database to MyISAM (eventually packed). The only issue was that for one of the table, we were talking of 5 TB of data, 23B rows. Not small… I calculated that with something like insert into MyISAM_table… select * from Innodb_table… would take [...]

Filed Under: MySQL

MySQL 5.6.7-RC in tpcc-mysql benchmark

October 8, 2012 By 21 Comments

MySQL 5.6.7 RC is there, so I decided to test how it performs in tpcc-mysql workload from both performance and stability standpoints. I can’t say that my experience was totally flawless, I bumped into two bugs: MySQL 5.6.7 locks itself on CREATE INDEX MySQL 5.6.7-rc crashed under tpcc-mysql workload But at the end, is not [...]

Filed Under: Benchmarks, MySQL

Review of MySQL 5.6 Defaults Changes

October 8, 2012 By 10 Comments

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 / [...]

Filed Under: Insight for DBAs, MySQL

Tools and Techniques for Index Design Webinar Questions Followup

October 4, 2012 By 5 Comments

I presented a webinar this week to give an overview of Tools and Techniques for Index Design. Even if you missed the webinar, you can register for it, and you’ll be emailed a link to the recording. I’d like to invite folks who are interested in tools for query optimization to attend the new Percona [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL

Logging Deadlock errors

September 19, 2012 By 4 Comments

The principal source of information for InnoDB diagnostics is the output of SHOW ENGINE INNODB STATUS but there are some sections that are not very useful. For example, LATEST DETECTED DEADLOCK only shows, as the name implies, the latest error detected. If you have 100 deadlocks per minute you will be able to see only [...]

Filed Under: Insight for Developers, MySQL

The Math of Automated Failover

September 18, 2012 By 9 Comments

There are number of people recently blogging about MySQL automated failover, based on production incident which GitHub disclosed. Here is my take on it. When we look at systems providing high availability we can identify 2 cases of system breaking down. First is when the system itself has a bug or limitations which does not [...]

Filed Under: Insight for DBAs, MySQL
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