InnoDB buffer pool is the most important memory area to allocate. It contains the most frequently read data and index entries from InnoDB tables. Its size is determined by innodb_buffer_pool_size, which is one of the two most important settings for...
One of the first problems one finds with automation is building custom configuration files. Don't worry though: it's a simple problem to solve. In this article we discuss how to use Ansible templates to generate proper my.cnf files for each MariaDB host. The template...
Many teams run Ansible plays from their laptops. In practice this just works, but this doesn't mean that it's an ideal way of using Ansible. Instead, we suggest to run it inside a dedicated host. In this article you'll find some good reason for that. Security...
It is not uncommon for an application to use WHERE conditions like this: WHERE status = 'DELETED' OR status IS NULL If you run EXPLAIN, such conditions typically only cause the type column to be show ref_or_null. Whereas, without the...
AUTO_INCREMENT primary keys are useful, because they save us the trouble to generate a unique value for every row, delegating this task to the database. But when we reach the limit we need to take some action, or we won’t be able to insert more rows. On 5 May...
Infrastructure As Code is a paradigm that consists of describing our infrastructure (servers and their configuration) as code that is understood by automation software like Ansible, Puppet, Terraform, and so on. Automation software can then be used to recreate the...
Sometimes it is possible to do with one query what most people would do with two or more queries. This is done by using expressive SQL syntax that is often ignored. This principle applies to any database, but this article focuses on MySQL and MariaDB syntax. Why...
A traditional software release circle starts with intensive development. The release early, release often model suggests to release incomplete, unstable versions as early as possible, making it very clear that they shouldn't be used in production. At some point the...
In the article What does NULL mean in SQL? I explained why I consider SQL NULL inconsistent. As a general rule, I should have made clear that I don’t think it is a good idea to use NULL, even if columns are NULLable by default in SQL. However, there are...
Transactions are the least known RDBMS features. Everyone knows they exist, but few know how they work. For this reason, it is not obvious that they can be read only. This article explains what read only transactions are and why we should use them when appropriate....
