On one of the clusters at Spil we noticed a sudden increase in the length of the history list and a steep increase in the ibdata file in the MySQL directory.
I did post a bit about this topic earlier regarding MySQL 5.5 but this cluster is still running 5.1 and unfortunately 5.1 does not have the same configurable options to influence the purging of the undo log…

Now I did find a couple of great resources that explain the purge lag problem into detail: Pythian,

Read the original article at Book Review – Effective MySQL

Effective MySQL: Optimizing SQL Statements by Ronald Bradford No Nonsense, Readable, Practical, and Compact I like that this book is small; 150 pages means you can carry it easily.  It’s also very no nonsense.  It does not dig too deeply into theory unless it directly relates to your day-to-day needs.  And those needs probably cluster [...]

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MySQL databases are great work horses of the internet.  They back tons of modern websites, from blogs and checkout carts, to huge sites like Facebook.  But these technologies don't run themselves.  When you're faced with a system that is slowing down, you'll need the right tools to diagnose and troubleshoot the problem.  MySQL has a huge community following and that means scores of great tools for your toolbox. Here are 7 ways to troubleshoot MySQL.

1. Use innotop

Innotop is a great tool for MySQL which despite the name monitors MySQL generally as well as InnoDB usage.  It's fairly easy to install, just download the perl script. Be sure to include a [client] section to your local users .my.cnf file (you have one don't you?).  Inside that section, place one line with "user=xyz" and one line with "password=abc".

If you're concerned that

There are a lot of scalability challenges we see with clients over and over. The list could easily include 20, 50 or even 100 items, but we shortened it down to the biggest five issues we see.

1. Tune those queries

By far the biggest bang for your buck is query optimization. Queries can be functionally correct and meet business requirements without being stress tested for high traffic and high load. This is why we often see clients with growing pains, and scalability challenges as their site becomes more popular. This also makes sense. It wouldn't necessarily be a good use of time to tune a query for some page off in a remote corner of your site, that didn't receive

The MySQL database is a crucial part of a wide variety of products, particularly web applications. Naturally, it is very important to monitor the health status of MySQL.  However, there is constant disagreement on which of the many MySQL status variables provide the best overview on MySQL health status and indicate that something is not right with a server.

It certainly depends on what your application does – tuning read performance is different than optimizing write operations and everything changes when you have a cluster. The average user can use small subset of variables while advanced user want to get more detailed picture of the situation. So there cannot be one set of “magic variables” to quietly optimize every situation. However, it is possible to have

I hope everyone is enjoying summertime, at least in the northern hemisphere. I’m about to head out to the pool, but before I go, here is a summary of this week’s blog posts.

1. Introduction to Perl interface for Monitis API
Monitis announces a simple way to access its API through Perl, a high-level, general-purpose, interpreted, dynamic programming language. This post demonstrates some examples for using the API with Perl and describes some of the benefits of the programming language. The source can be found on our Github page.

2. 101 Tips to