Thanks for all, who attended my webinar, I got many questions and I wanted to take this opportunity to answer them. Q: Even ntp has a delay of 0.3-0.4 between servers does that mean a 0.25 as from logs can be an issue ? A: My demo vms were running for a few hours before [...]
Edge-case behavior of INSERT…ODKU
October 27, 2012 By 6 Comments
A few weeks back, I was working on a customer issue wherein they were observing database performance that dropped through the floor (to the point of an outage) roughly every 4 weeks or so. Nothing special about the environment, the hardware, or the queries; really, the majority of the database was a single table with [...]
Write contentions on the query cache
September 5, 2012 By 5 Comments
While doing a performance audit for a customer a few weeks ago, I tried to improve the response time of their top slow query according to pt-query-digest‘s report. This query was run very frequently and had very unstable performance: during the time data was collected, response time varied from 50µs to 1s. When I ran [...]
SQL Injection Questions Followup
July 26, 2012 By 2 Comments
I presented a webinar today about SQL Injection, to try to clear up some of the misconceptions that many other blogs and articles have about this security risk. You can register for the webinar even now that I’ve presented it, and you’ll be emailed a link to the recording, which will be available soon. During [...]
DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
Suppose you have turned on innodb_file_per_table (which means that each table has its own tablespace), and you have to drop tables in a background every hour or every day. If its once every day then you can probably schedule the table dropping process to run during off-peak hours. But I have seen cases where the [...]
Announcement of Percona XtraDB Cluster 5.5.20 GA release
April 3, 2012 By 11 Comments
I am excited to announce the availability of the GA release of our new product Percona XtraDB Cluster. Percona XtraDB Cluster is a High Availability and Scalability solution for MySQL Users and is based on Percona Server 5.5.20. With this release we make clustering very easy and affordable for everyone. You can convert your existing [...]
ext4 vs xfs on SSD
March 15, 2012 By 26 Comments
As ext4 is a standard de facto filesystem for many modern Linux system, I am getting a lot of question if this is good for SSD, or something else (i.e. xfs) should be used. Traditionally our recommendation is xfs, and it comes to known problem in ext3, where IO gets serialized per i_node in O_DIRECT [...]
MLC SSD card lifetime and write amplification
November 15, 2011 By 8 Comments
As MLC-based SSD cards are raising popularity, there is also a raising concern how long it can survive. As we know, a MLC NAND module can handle 5,000-10,000 erasing cycles, after which it gets unusable. And obviously the SSD card based on MLC NAND has a limited lifetime. There is a lot of misconceptions and [...]
Benchmarking Galera replication overhead
October 13, 2011 By 12 Comments
When I mention Galera replication as in my previous post on this topic, the most popular question is how does it affect performance. Of course you may expect performance overhead, as in case with Galera replication we add some network roundtrip and certification process. How big is it ? In this post I am trying [...]
MySQL versions shootout
October 10, 2011 By 6 Comments
As part of work on “High Performance MySQL, 3rd edition”, Baron asked me to compare different MySQL version in some simple benchmark, but on decent hardware. So why not.
