May 20, 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 [...]

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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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Is there room for more MySQL IO Optimization?

January 3, 2013 By 11 Comments

I prefer to run MySQL with innodb_flush_method=O_DIRECT in most cases – it makes sure there is no overhead of double buffering and I can save the limited amount of file system cache I would normally have on database server for those things which need to be cached — system files, binary log, FRM files, MySQL [...]

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MySQL Wish for 2013 – Better Memory Accounting

December 31, 2012 By 6 Comments

With Performance Schema improvements in MySQL 5.6 I think we’re in the good shape with insight on what is causing performance bottlenecks as well as where CPU resources are spent. (Performance Schema does not accounts CPU usage directly but it is something which can be relatively easily derived from wait and stage information). Where we’re [...]

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

Edge-case behavior of INSERT…ODKU

October 27, 2012 By 6 Comments

A few weeks back, I was working on a customer issue wherein they were observing database performance that dropped through the floor (to the point of an outage) roughly every 4 weeks or so. Nothing special about the environment, the hardware, or the queries; really, the majority of the database was a single table with [...]

Filed Under: Insight for DBAs, Insight for Developers, 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

Distro Packages, Pre-built Binaries or Compile Your Own MySQL

September 4, 2012 By 7 Comments

I’ve been helping customers deploy and maintain MySQL (and variants) for the last couple of years and it has always been interesting to hear customer thoughts on how they want their servers installed. It has also been asked many times not only by our support and consulting customers, but widely from different forums and blogs [...]

Filed Under: MySQL

Hidden columns of query_review_history table

August 28, 2012 By Leave a Comment

You can use pt-query-digest to process a MySQL slow query log and store historical values for review trend analysis into query_review_history table. According to its official documentation you can populate many columns in that table but there are other important ones such as ‘user’, ‘host’, ‘db’ which are not included by default. I will explain [...]

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Recovery deleted ibdata1

August 10, 2012 By 9 Comments

Recently I had a case when a customer deleted the InnoDB main table space – ibdata1 – and redo logs – ib_logfile*. MySQL keeps InnoDB files open all the time. The following recovery technique is based on this fact and it allowed to salvage the database. Actually, the files were deleted long time ago – [...]

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MySQL Upgrade Webinar Questions Followup

June 28, 2012 By 7 Comments

I did a Webinar about MySQL Upgrade – Best Practices Yesterday and there were some questions we could not answer during Webinar, following Jay’s Lead I decided to post them as a Blog Post. Q: Can you go directly MySQL 5.0 to 5.5 for MyISAM tables? MyISAM have not been getting any significant development since [...]

Filed Under: Insight for DBAs, MySQL
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