November 1, 2014

How to Monitor MySQL with Percona’s Nagios Plugins

In this post, I’ll cover the new MySQL monitoring plugins we created for Nagios, and explain their features and intended purpose. I want to add a little context. What problem were we trying to solve with these plugins? Why yet another set of MySQL monitoring plugins? The typical problem with Nagios monitoring (and indeed with […]

Troubleshooting MySQL Upgrade Performance Regressions

So lets say you upgraded from MySQL 5.1 to Percona Server 5.5 and instead of expected performance improvement you see your performance being worse. What should you do ? First if you followed MySQL upgrade best practices such as testing your workload with pt-upgrade the chances of this happening are rather slim. But lets assume […]

Reasons for MySQL Replication Lag

One common theme in the questions our MySQL Support customers ask is MySQL Replication Lag. The story is typically along the lines everything is same as before and for some unknown reason the slave is started to lag and not catching up any more. I always smile at “nothing has changed” claim as it usually […]

What’s required to tune MySQL?

I got a serendipitous call (thanks!) yesterday asking what would be needed to tune[1] a database for better performance. It is a question that I hear often, but I never thought about answering it in public. Here’s a consolidated version of what I explained during our conversation.

How to Identify Bad Queries in MySQL

Finding bad queries is a big part of optimization. A scientific optimization process can be simplified to “can anything be improved for less than it costs not to improve it? – if not, we’re done.” In databases, we care most about the work the database is doing. That is, queries. There are other things we […]

Why you should ignore MySQL’s key cache hit ratio

I have not caused a fist fight in a while, so it’s time to take off the gloves. I claim that somewhere around of 99% of advice about tuning MySQL’s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key buffer hit ratio, and […]

Air traffic queries in MyISAM and Tokutek (TokuDB)

This is next post in series Analyzing air traffic performance with InfoBright and MonetDB Air traffic queries in LucidDB Air traffic queries in InfiniDB: early alpha Let me explain the reason of choosing these engines. After initial three posts I am often asked “What is baseline ? Can we compare results with standard MySQL engines […]

Beware of MySQL Data Truncation

Here is nice gotcha which I’ve seen many times and which can cause just a minefield for many reasons. Lets say you had a system storing articles and you use article_id as unsigned int. As the time goes and you see you may get over 4 billions of articles you change the type for article_id […]

How Percona does a MySQL Performance Audit

Our customers or prospective customers often ask us how we do a performance audit (it’s our most popular service). I thought I should write a blog post that will both answer their question, so I can just reply “read all about it at this URL” and share our methodology with readers a little bit. This […]

MySQL 6.0 vs 5.1 in TPC-H queries

Last week I played with queries from TPC-H benchmarks, particularly comparing MySQL 6.0.4-alpha with 5.1. MySQL 6.0 is interesting here, as there is a lot of new changes in optimizer, which should affect execution plan of TPC-H queries. In reality only two queries (from 22) have significantly better execution time (about them in next posts), […]