May 19, 2013

More on MySQL transaction descriptors optimization

April 26, 2013 By Leave a Comment

Since my first post on MySQL transaction descriptors optimization introduced in Percona Server 5.5.30-30.2 and a followup by Dimitri Kravchuk, we have received a large number of questions on why the benchmark results in both posts look rather different. We were curious as well, so we tried to answer that question by retrying benchmarks on [...]

Filed Under: Benchmarks, MySQL Tagged With: ,

High-load problems? Investigate them with ‘pt-query-digest’

April 23, 2013 By 2 Comments

I had the chance to work on an interesting case last week, and I thought I’d share what I think is a little known goodie from Percona Toolkit for MySQL called pt-query-digest. One customer was suffering from periods of high load on their database server, leading to degraded application performance, and sometimes even short moments [...]

Filed Under: MySQL Tagged With: , ,

MySQL 5.6 – InnoDB Memcached Plugin as a caching layer

March 29, 2013 By 10 Comments

A common practice to offload traffic from MySQL 5.6 is to use a caching layer to store expensive result sets or objects.  Some typical use cases include: Complicated query result set (search results, recent users, recent posts, etc) Full page output (relatively static pages) Full objects (user or cart object built from several queries) Infrequently [...]

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Sphinx search performance optimization: attribute-based filters

January 15, 2013 By 9 Comments

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 [...]

Filed Under: Insight for Developers, MySQL Tagged With: , ,

The Optimization That (Often) Isn’t: Index Merge Intersection

December 14, 2012 By 6 Comments

Prior to version 5.0, MySQL could only use one index per table in a given query without any exceptions; folks that didn’t understand this limitation would often have tables with lots of single-column indexes on columns which commonly appeared in their WHERE clauses, and they’d wonder why the EXPLAIN plan for a given SELECT would [...]

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

Minimizing Downtime from Lengthy AWS Outages

October 24, 2012 By 6 Comments

Well, it happened again…  Another lengthy EBS outage in the US-East region impacted several sites across the net.  While failures like this are rare, they can be quite costly and translate into headaches for the operations team when impact production systems for any length of time.  At Percona, we routinely help clients architect and deploy [...]

Filed Under: Cloud and NoSQL, 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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Load management Techniques for MySQL

May 6, 2012 By 3 Comments

One of the very frequent cases with performance problems with MySQL is what they happen every so often or certain times. Investigating them we find out what the cause is some batch jobs, reports and other non response time critical activities are overloading the system causing user experience to degrade. The first thing you need [...]

Filed Under: Insight for DBAs, MySQL

How FLUSH TABLES WITH READ LOCK works with Innodb Tables

March 23, 2012 By 20 Comments

Many backup tools including Percona Xtrabackup, MyLVMBackup and others use FLUSH TABLES WITH READ LOCK to temporary make MySQL read only. In many cases the period for which server has to be made read only is very short, just few seconds, yet the impact of FLUSH TABLES WITH READ LOCK can be quite large because [...]

Filed Under: Insight for DBAs, MySQL

Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

March 21, 2012 By 10 Comments

This is the second blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is aimed at the optimizer enhancement Multi Range Read (MRR). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take a look at [...]

Filed Under: Benchmarks, Insight for DBAs, MySQL Tagged With: , , , , , , , , , , , , , ,
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