Posted by Sheeri Cabral on Mar 1, 2010
Baron makes an excellent point in Why you should ignore MySQL’s key cache hit ratio — ratio is not the same as rate. Furthermore, rate is [often] the important thing to look at.
This is something that, at Pythian, we internalized a long time ago when thinking about MySQL tuning. In fact, mysqltuner 2.0 takes this into account, and the default configuration includes looking at both ratios and rates.
If I told you that your database had a ratio of temporary tables written to disk of 20%, you might think “aha, my database is slow because of a lot of file I/O caused by writing temporary tables to disk!”. However, that 20% ratio may actually mean a rate of 2 per hour — which is most likely not causing excessive I/O.
To get a sense of this concept, and also how mysqltuner works, I will show the lines from the mysqltuner default configuration that deal with temporary tables written to disk. Read the rest of this entry . . .
Posted by Sheeri Cabral on Aug 27, 2009
In record time, less than a week after the conference (thanks to the free Pinnacle Video Spin and YouTube), all 11 videos that were taken at OpenSQLCamp Europe are online.
For those who missed the sessions, or just want to relive the fun!
Almost all the sessions were filmed; regrettably Darren Cassar’s Securich – MySQL user administration and security made easy! and Stephane Combaudon’s Minimizing data access with covering indexes were not.
The YouTube videos have the descriptions and resources from the official conference pages, and links to pages. If there is more information to add (for example, the slides from a talk are now online), or if you spot an error, please feel free to add a comment on the YouTube video, or as a comment to this blog post.
Individual presentations:
Enjoy!
Posted by Danil Zburivsky on Oct 9, 2008
Quite often we need to perform a so-called “MySQL instance audit”. This common DBA procedure should give you a general view of the MySQL environment. You may be interested in a basic understanding of what kind of operation MySQL performs, how much memory does it use, or how well does it look from the performance point of view. There is no easy out-of-the-box way to do such an audit on a MySQL server. You can use SHOW STATUS and check the list of system variables, but this way can hardly be called DBA-friendly.
Fortunately there are several tools to make this process easier. Among most popular are mysqlreport and MySQLTuner. In this post I’d like to give a brief overview of MySQLTuner.
So, what can MySQLTuner do? Quoting the documentation: “MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability. Within seconds, it will display statistics about your MySQL installation and the areas where it can be improved.”
It’s not magic — they don’t use any “hidden” or unknown MySQL features to provide the report. What they do is use SHOW STATUS metrics and provide a user-friendly report, interpreting data this or that way. What makes such tools really valuable is the way they interpret that data.
Read the rest of this entry . . .
