The MySQL manual tells us that regardless of whether or not we use “SET FOREIGN_KEY_CHECKS=0″ before making schema changes, InnoDB will not allow a column referenced by a foreign key constraint to be modified in such a way that the foreign key will reference a column with a mismatched data type. For instance, if we [...]
This post is a step-by-step guide to set up Percona XtraDB Cluster (PXC) in a virtualized test sandbox. I used Amazon EC2 micro instances, but the content here is applicable for any kind of virtualization technology (for example VirtualBox). The goal is to give step by step instructions, so the setup process is understandable and [...]
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 [...]
Following my previous benchmarks of SATA SSD cards I got Intel SSD 520 240GB into my hands. In this post I show the results of raw IO performance of this card.
Following my previous benchmark of Samsung 830, today I want to show results for STEC MACH16 SATA card, 200GB size, this card is based on SLC, and regarding STEC website, it is an enterprise grade storage.
I personally like PCIe based Flash, but from a pricing point our customers are looking for cheaper alternatives. SATA SSD is an options. There is many products based on MLC technology, and Intel 320 I would say is the most popular. I do not particularly like its write performance – I wrote about it before, [...]
Working on customer case today I ran into interesting problem – query joining about 20 tables (thank you ORM by joining all tables connected with foreign keys just in case) which would take 5 seconds even though in the read less than 1000 rows and doing it completely in memory. The plan optimizer picked was [...]
This is the third 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 targeted at the join related optimizations introduced in the optimizer. These optimizations are available in both MySQL 5.6 and MariaDB 5.5, and MariaDB 5.5 [...]
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 [...]
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 [...]