I recently mentioned a few of the big “non-starter” limitations Postgres has overcome for specific use cases. I decided to write a series of blog posts on MySQL’s unsolved severe limitations. I mean limitations that really hobble it for major, important needs — not in areas where it isn’t used, but in areas where it [...]
Cache Miss Storm
September 10, 2010 By 30 Comments
I worked on the problem recently which showed itself as rather low MySQL load (probably 5% CPU usage and close to zero IO) would spike to have hundreds instances of threads running at the same time, causing intense utilization spike and server very unresponsive for anywhere from half a minute to ten minutes until everything [...]
Estimating Replication Capacity
July 20, 2010 By 4 Comments
It is easy for MySQL replication to become bottleneck when Master server is not seriously loaded and the more cores and hard drives the get the larger the difference becomes, as long as replication remains single thread process. At the same time it is a lot easier to optimize your system when your replication runs [...]
On Good Instrumentation
May 31, 2010 By 1 Comment
In so many cases troubleshooting applications I keep thinking how much more efficient things could be going if only there would be a good instrumentation available. Most of applications out there have very little code to help understand what is going on and if it is there it is frequently looking at some metrics which [...]
Watch out for your CRON jobs
October 14, 2009 By 19 Comments
Resolving extreme database overload for the customer recently I have found about 80 copies of same cron job running hammering the database. This number is rather extreme typically the affect is noticed and fixed well before that but the problem with run away cron jobs is way to frequent. If slow down happens on the [...]
The perils of InnoDB with Debian and startup scripts
January 28, 2009 By 13 Comments
Are you running MySQL on Debian or Ubuntu with InnoDB? You might want to disable /etc/mysql/debian-start. When you run /etc/init.d/mysql start it runs this script, which runs mysqlcheck, which can destroy performance. It can happen on a server with MyISAM tables, if there are enough tables, but it is far worse on InnoDB. There are [...]
Goal driven performance optimization
December 22, 2008 By Leave a Comment
When your goal is to optimize application performance it is very important to understand what goal do you really have. If you do not have a good understanding of the goal your performance optimization effort may well still bring its results but you may waste a lot of time before you reach same results as [...]
MySQL QA Team Benchmarks for MySQL 5.1.30
December 13, 2008 By 12 Comments
As you might have seen MySQL QA Team has published their benchmarks for MySQL 5.0.72 and 5.1.30. It is interesting to compare with results I posted previously
Living with backups
November 6, 2008 By 28 Comments
Everyone does backups. Usually it’s some nightly batch job that just dumps all MySQL tables into a text file or ordinarily copies the binary files from the data directory to a safe location. Obviously both ways involve much more complex operations than it would seem by my last sentence, but it is not important right [...]
To find the bottleneck, stop guessing and start measuring
August 4, 2008 By 8 Comments
We recently examined a customer’s system to try to speed up an ETL (Extraction, Transformation and Loading) process for a big data set into a sort of datamart or DW. What we typically do is ask customers to run the process in question, and then examine what’s happening. In this case, the (very large, powerful) [...]
