Search Results for: how to select second max value in the table

Benchmarking Percona Server TokuDB vs InnoDB

After compiling Percona Server with TokuDB, of course I wanted to compare InnoDB performance vs TokuDB. I have a particular workload I’m interested in testing – it is an insert-intensive workload (which is TokuDB’s strong suit) with some roll-up aggregation, which should produce updates in-place (I will use INSERT .. ON DUPLICATE KEY UPDATE statements […]

Investigating MySQL Replication Latency in Percona XtraDB Cluster

I was curious to check how Percona XtraDB Cluster behaves when it comes to MySQL replication latency — or better yet, call it data propagation latency. It was interesting to see whenever I can get stale data reads from other cluster nodes after write performed to some specific node. To test it I wrote quite a […]

Review of MySQL 5.6 Defaults Changes

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 / […]

Percona XtraDB Cluster reference architecture with HaProxy

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 […]

A case for MariaDB’s Hash Joins

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 […]

Join Optimizations in MySQL 5.6 and MariaDB 5.5

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 […]

How To Test Your Upgrades – pt-upgrade

Upgrades are usually one of the biggest part of any database infrastructure maintenance. Even with enough planning something else can go bad after sending your production application to the version you’ve upgraded to. Let’s look at how one Percona Toolkit tool, pt-upgrade can help you identify what to expect and test your upgrades better which […]