As we know different storage engines in MySQL have different file structures. Every table in MySQL 5.6 must have a .frm file in the database directory matching the table name. But where the rest of the data resides depends on the storage engine. For MyISAM we have .MYI and .MYD files in the database directory […]
One of the common causes of downtime with MySQL is running out of connections. Have you ever seen this error? “ERROR 1040 (00000): Too many connections.” If you’re working with MySQL long enough you surely have. This is quite a nasty error as it might cause complete downtime… transient errors with successful transactions mixed with […]
If you try to install the TokuDB storage engine on a modern Linux distribution it might fail with following error message: 2014-07-17 19:02:55 13865 [ERROR] TokuDB will not run with transparent huge pages enabled. 2014-07-17 19:02:55 13865 [ERROR] Please disable them to continue. 2014-07-17 19:02:55 13865 [ERROR] (echo never > /sys/kernel/mm/transparent_hugepage/enabled) You might be curious […]
Earlier this month I wrote about vmstat iowait cpu numbers and some of the comments I got were advertising the use of util% as reported by the iostat tool instead. I find this number even more useless for MySQL performance tuning and capacity planning. Now let me start by saying this is a really tricky and deceptive number. Many […]
The Percona Backup Service managed service launched today. It ensures properly configured backups run successfully as scheduled on customer provided backup storage – whether on premise, in the cloud, or a hybrid. Backup issues or production data recovery are efficiently handled by Percona Managed Services technicians with deep knowledge of MySQL. As we state in […]
The architecture of MySQL-powered applications is one of my favorite topics to talk about. It’s a very important topic because if you do not get the architecture right then you’re very likely to fail with your project – either from the standpoint of failing with performance, high availability or security requirements… or failing to deliver […]
I’ve been running a benchmark today on my old test box with conventional hard drives (no raid with BBU) and noticed something unusual in the CPU utilization statistics being reported. The benchmark was run like this:
sysbench --num-threads=64 --max-requests=0 --max-time=600000 --report-interval=10 --test=oltp --db-driver=mysql --oltp-dist-type=special --oltp-table-size=1000000 --mysql-user=root --mysql-password=password run
Which means: create 64 threads and hammer the database with queries as quickly as possible. As the test […]
MySQL has status variables “questions” and “queries” which are rather close but also a bit different, making it confusing for many people. The manual describing it might not be very easy to understand:
The number of statements executed by the server. This variable includes statements executed within stored programs, unlike the Questions variable. It does not count COM_PING or COM_STATISTICS commands.
The number of statements executed by the server. This includes only statements sent to the server by clients and not statements executed within stored programs, unlike the Queries variable. This variable does not count COM_PING, COM_STATISTICS, COM_STMT_PREPARE, COM_STMT_CLOSE, or COM_STMT_RESET commands.
In a nutshell if you’re not using prepared statements the big difference between those is what “Questions” would count stored procedure calls as […]
Achieving the best possible MySQL Performance doesn’t have to be complicated. It’s all about knowing which tools are designed for the task at hand – along with some basic (yet often overlooked) best practices. Join me Wednesday, May 14 at 10 a.m. Pacific for a free webinar titled, “Practical MySQL performance optimization.” I’ll be sharing […]
Later this week I’m excited to depart on a trip to South America. First I will stop in Montevideo, Uruguay, to meet with Percona’s team out there as well as to participate in our next Percona University event on April 29. For those who do not know, Percona University events are free to attend and […]