Be careful with my findings, I appear to have compile in debug mode, I am redoing the benchmarks. Updated version here. I recently had to work with many customers having large number of connections opened in MySQL and although I told them this was not optimal, I had no solid arguments to present. More than [...]
MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
This is the third in a series on what’s seriously limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL handles connections, allocating one thread per connection to the server.
Why you should ignore MySQL’s key cache hit ratio
February 28, 2010 By 28 Comments
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 [...]
Improving InnoDB recovery time
July 7, 2009 By 12 Comments
Speed of InnoDB recovery is known and quite annoying problem. It was discussed many times, see: http://bugs.mysql.com/bug.php?id=29847 http://dammit.lt/2008/10/26/innodb-crash-recovery/ This is problem when your InnoDB crashes, it may takes long time to start. Also it affects restoring from backup (both LVM and xtrabackup / innobackup) In this is simple test, I do crash mysql during in-memory [...]
5.0.75-build12 Percona binaries
January 23, 2009 By 18 Comments
After several important fixes to our patches we made binaries for build12. Fixes include: Control of InnoDB insert buffer to address problems Peter mentioned http://www.mysqlperformanceblog.com/2009/01/13/some-little-known-facts-about-innodb-insert-buffer/, also check Bug 41811 to see symptoms of problem with Insert buffer. http://www.percona.com/docs/wiki/patches:innodb_io_patches * innodb_flush_neighbor_pages (default 1) – When the dirty page are flushed (written to datafile), this parameter determines [...]
How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
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 [...]
Debugging sleeping connections with MySQL
February 8, 2007 By 30 Comments
Have you ever seen connection in the SHOW PROCESSLIST output which is in “Sleep” state for a long time and you have no idea why this would happen ? I see if frequently with web applications and it is often indication of trouble. Not only it means you may run out of MySQL connections quicker [...]
InnoDB vs MyISAM vs Falcon benchmarks – part 1
January 8, 2007 By 117 Comments
Several days ago MySQL AB made new storage engine Falcon available for wide auditory. We cannot miss this event and executed several benchmarks to see how Falcon performs in comparison to InnoDB and MyISAM. The second goal of benchmark was a popular myth that MyISAM is faster than InnoDB in reads, as InnoDB is transactional, [...]
InnoDB benchmarks
January 3, 2007 By 15 Comments
There was several changes in InnoDB to fix scalabilty problems, so I ran benchmark to check new results and also compare overall performance of InnoDB in 5.0 and 5.1 before and after fixes. Problems in InnoDB that were fixed: Thread trashing issues with count of theads 100+. In this case performance of InnoDB degraded dramatically. [...]
Are PHP persistent connections evil ?
November 12, 2006 By 32 Comments
As you probably know PHP “mysql” extension supported persistent connections but they were disabled in new “mysqli” extension, which is probably one of the reasons some people delay migration to this extension. The reason behind using persistent connections is of course reducing number of connects which are rather expensive, even though they are much faster [...]
