May 25, 2013

MySQL 5.5 and MySQL 5.6 default variable values differences

February 21, 2013 By 8 Comments

As the part of analyzing surprising MySQL 5.5 vs MySQL 5.6 performance results I’ve been looking at changes to default variable values. To do that I’ve loaded the values from MySQL 5.5.30 and MySQL 5.6.10 to the different tables and ran the query:

Lets go over to see what are the most important changes [...]

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

Implications of Metadata Locking Changes in MySQL 5.5

February 1, 2013 By 9 Comments

While most of the talk recently has mostly been around the new changes in MySQL 5.6 (and that is understandable), I have had lately some very interesting cases to deal with, with respect to the Metadata Locking related changes that were introduced in MySQL 5.5.3. It appears that the implications of Metadata Locking have not [...]

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

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 [...]

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

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

Question of the week: Maximum number of tables per MySQL instance.

November 16, 2012 By 5 Comments

I’ve got the great response to my two previous polls (1,2) so lets continue learning about how we all use MySQL. The question of this week is What is the maximum number of tables per MySQL instance do you use ? Thank you for participating!

Filed Under: Insight for DBAs, MySQL, Polls

Percona XtraDB Cluster – installation and setup webinar follow up Q&A

October 28, 2012 By 4 Comments

Thanks for all, who attended my webinar, I got many questions and I wanted to take this opportunity to answer them. Q: Even ntp has a delay of 0.3-0.4 between servers does that mean a 0.25 as from logs can be an issue ? A: My demo vms were running for a few hours before [...]

Filed Under: MySQL, XtraDB Cluster

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

How to find MySQL queries worth optimizing ?

September 11, 2012 By 6 Comments

One question I often get is how one can find out queries which should be optimized. By looking at pt-query-digest report it is easy to find slow queries or queries which cause the large portion of the load on the system but how do we know whenever there is any possibility to make this query [...]

Filed Under: Insight for DBAs, MySQL

A case for MariaDB’s Hash Joins

May 31, 2012 By Leave a Comment

MariaDB 5.3/5.5 has introduced a new join type “Hash Joins” which is an implementation of a Classic Block-based Hash Join Algorithm. In this post we will see what the Hash Join is, how it works and for what types of queries would it be the right choice. I will show the results of executing benchmarks [...]

Filed Under: Benchmarks, Insight for DBAs, MySQL Tagged With: , , , , ,
« Older Posts
Newer Posts »