Join 28,000 others and follow Sean Hull on twitter @hullsean. MySQL slow query on RDS If you run MySQL as your backend datastore is there one thing you can do to improve performance across the application?. Those SQL queries are surely key. And the quickest way to find the culprits is to regularly analyze your […]

So I noticed a few different questions and posts about parsing a string out of another string recently. While some solutions included creating new functions and etc it can also be done within a single query in some cases.

For example, let us say that we are looking to pull out the domain from a URL. I will try to go into detail as to why and how this works.
We have the following table.

CREATE TABLE `parse_example` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `urldemo` varchar(150) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB;
+----+----------------------------+
| id | urldemo                    |
+----+----------------------------+
|  1 | http://www.mysql.com/      |
|  2 | …

Nos gustaría desearte unas felices fiestas en nombre del equipo de DBAHire.com. ¡Que todos vuestros sueños se hagan realidad en el 2015!

Fotografía tomada en el mercado de navidad de Valencia (España) en diciembre de 2014.

¡Que vuestras innodb_buffer_pool_reads sean bajas y vuestro Uptime alto en 2015!

We would like to wish you a happy holidays on behalf of the DBAHire.com team. May all your dreams come true in 2015!

Photograph taken at the Christmas market of Valencia (Spain) in December 2014.

May your MySQL innodb_buffer_pool_reads be low and your Uptime high in 2015.

This blog aims to make a performance comparison between the different MySQL versions/editions and also comparing the differents MySQL forks such as Percona Server and MariaDB.  Indeed number of improvements as been done to innodb storage engine in the last MySQL versions. You can find below some of the performance improvements applied to InnoDB these last years (non exhaustive list):

MySQL 5.0

1. New compact storage format which can save up to 20% of the disk space required in previous MySQL/InnoDB versions.
2. Faster recovery from a failed or aborted ALTER TABLE.
3. Faster implementation of TRUNCATE TABLE.

MySQL 5.5

1. MySQL Enterprise Thread Pool, As of MySQL 5.5.16, MySQL Enterprise Edition distributions include a thread pool plugin that provides an alternative thread-handling model designed to reduce overhead and improve performance.
2. …

Podcasts Learning Performance Server Tuning

In this episode we finish our series on MaxScale. Ear candy is about using MySQL and Galera for geographic replication, and at the Movies uses MySQL to build big data applications.

Podcasts Learning Performance Server Tuning

In this episode we finish our series on MaxScale. Ear candy is about using MySQL and Galera for geographic replication, and at the Movies uses MySQL to build big data applications.

Does your dataset consist of InnoDB tables with large BLOB data such that the data is stored in external BLOB pages? Was the dataset created in MySQL version 5.1 and below and without using the InnoDB plugin, or with InnoDB plugin but with MySQL version earlier than 5.1.55? If the answer to both the questions are "YES" then it could very well be that you have a hidden corruption lying around in your dataset.

The post Beware of MySQL BLOB Corruption in Older Versions appeared first on ovais.tariq.

It has been a while since I have looked at InnoDB crash recovery. A lot has change in the last few years – we have serious crash recovery performance improvements in MySQL 5.5 and MySQL 5.6, we have solid state drives raising as typical high performance IO subsystem and we also have the ability to set much larger log files and often have a much larger InnoDB Buffer Pool to work with.

First let me revisit the challenge with have with InnoDB configuration. For write-intensive workloads it is extremely important to size innodb_log_file_size for good performance, however the longer log file size you have the longer you might have to wait for InnoDB to complete crash recovery, which impacts your recovery strategy.

How much can innodb_log_file_size impact performance? Massively! Doing intensive writes to a database that well fits in memory, I’d say there’s a 10x …

Does your dataset consist of InnoDB tables with large BLOB data such that the data is stored in external BLOB pages? Was the dataset created in MySQL version 5.1 and below and without using the InnoDB plugin, or with InnoDB plugin but with MySQL version earlier than 5.1.55? If the answer to both the questions are “YES” then it could very well be that you have a hidden corruption lying around in your dataset. The only way you would be able to find out about the corruption is when you have a crash with InnoDB assertion messages similar to the following:

InnoDB: Serious error! InnoDB is trying to free page 4
InnoDB: though it is already marked as free in the tablespace!
InnoDB: The tablespace free space info is corrupt.


In this post I will summarize what the bug is and how it corrupts the dataset. If you want more details of why and how the corruption manifests itself then you can additionally …