How can we fix a nasty out-of-space issue leveraging the flexibility of Percona Operator for MySQL?

When planning a database deployment, one of the most challenging factors to consider is the amount of space we need to dedicate to data on disk.

This is even more cumbersome when working on bare metal, as it is more difficult to add space when using this kind of solution with respect to the cloud.

When using cloud storage like EBS or similar, it is normally easy(er) to extend volumes, which gives us the luxury to plan the space to allocate for data with a good grade of relaxation. 

Is this also true when using a solution based on Kubernetes like Percona Operator for MySQL? Well, it depends on where you run it. However, if the platform you choose supports the option to extend volumes, K8s per se gives you the …

By having appropriate indexes on your MySQL tables, you can greatly enhance the performance of SELECT queries. But, did you know that adding indexes to your tables in itself is an expensive operation, and may take a long time to complete depending on the size of your tables? During this time, you are also likely to experience a degraded performance of queries as your system resources are busy in index-creation work as well. In this blog post, we discuss an approach to optimize the MySQL index creation process in such a way that your regular workload is not impacted.

MySQL Rolling Index Creation

We call this approach a ‘Rolling Index Creation’ - if you have a MySQL master-slave replica set, you can create the index one node at a time in a rolling fashion. You should create the index only on the slave nodes so the master’s …

dbdeployer went into release candidate status a few weeks ago. Since then, I added no new features, but a lot of tests. The test suite now runs 3,000+ tests on MacOS and a bit more on Linux, for a grand total of 6,000+ tests that need to run at least twice: once with concurrency enabled and once without. I know that testing can't prove the absence of bugs, but I am satisfied with the results, since all this grinding has allowed me to find several bugs and fix them.

In this framework, I felt that dbdeployer could exit candidate status and get to version 1.0. This happened on March 26th. An immediate side effect of this change is that from this point on, dbdeployer must adhere to the semantic versioning principles:

A version number is made of Major, Minor, and Revision. When changes are applied, the following happens:

…

Security features overview

One of Oracle's tenets is the focus on security. For this reason, when it took over the stewardship of MySQL, it started addressing the most common issues. It was not quick acting, but we have seen real progress:

1. MySQL 5.7 has removed the anonymous accounts, which was the greatest threat to security. Because of those accounts, and the default privileges granted to them, users without any privileges could access the "test" database and do serious damage. Additionally, because of the way the privilege engine evaluates accounts, anonymous users could hijack legitimate users, by preventing them to work …

We have been using SSH all the time but not all people really understand the files we put inside the ~/.ssh folder on our computer. It was a myth to me when I was first using SSH, but things are pretty clear to me now and I want to share this with all of you, just in case you don't know.

known_hosts

This file is responsible for verifying the host we have connected to. If it was the first time you connect to a host, you would probably see the following message:

The authenticity of host 'example.com (10.0.0.0)' can't be established.
RSA key fingerprint is    SHA256:VqgUG8v+gxrigR1csELYv6Un6l7HxMgPgMj9wyUr7G4.
Are you sure you want to continue connecting (yes/no)?

The moment you select yes to continue connecting, the hostname along with the public key of the server will be saved as a new line in this file. Why we need this file? Just imagine that for some reason our routing has …

Among the many New features introduced by MySQL 5.7, we can notice a strong trend towards improving the server security by default. Two features stand out in this respect:

• A password-less root is no longer the default for new installations. Unless you say otherwise, the default installers mysqld --initialize and the deprecated mysql_install_db will generate a random password which the user needs to change.
• The anonymous accounts are no longer created by default. When you start MySQL, you only get the root user (and a new one: read on).

The above features are a great advance not only for security but also for usability. The anonymous users were a continuous source of mismatched connections, …

Previous Episodes:

MySQL-Docker operations. - Part 1: Getting started with MySQL in DockerMySQL-Docker operations. - Part 2: Customizing MySQL in Docker
With the material covered in the first two articles, we have all the elements needed to set up replication in Docker. We just need to put the pieces together.
If you want to do everything by hand, it will only take a few minutes. The steps are not complicated. If you have followed the reasoning in the past episodes, you will know what to do.
Or, you can make your life easier by using the ready-made scripts available in Github as MySQL …

Previous Episodes:

• MySQL-Docker operations. - Part 1: Getting started with MySQL in Docker

After seeing the basics of deploying a MySQL server in Docker, in this article we will lay the foundations to customising a node and eventually using more than one server, so that we can cover replication in the next one.
Enabling GTID: the dangerous approach.To enable GTID, you need to set five variables in the database server:

• master-info-repository=table
• relay-log-info-repository=table
• enforce-gtid-consistency
• gtid_mode=ON
• log-bin=mysql-bin

For MySQL 5.6, you also need to set log-slave-updates, but we won't deal with such ancient versions here.
Using the method …

Docker is one of the fastest growing trends in IT. It allows fast deployment of services and applications on a Linux machine (and, with some limits, on other operating systems). Compared to other methods of deploying databases, such as virtual machines or application isolation, it offers faster operations and better performance.
Many people, surprised by the sudden advance of this technology, keep asking What is Docker? And why you should use it?
I will write soon an article with a deep comparison of the three methods (VM, container, sandbox), but for now, we should be satisfied with a few basic facts:

• Docker is a Linux container. It deploys every application as a series of binary …

During the PerconaLive conference in Amsterdam, I attended a session where I heard a good piece of advice about using GTID. It amounts to: look at SHOW SLAVE STATUS output, and if you see more than one line in the Executed_Gtid_Set field, this tells you immediately if someone has written on a slave database.
This is good advice. Let's dissect it. Here is what a regular slave looks like, when nobody has messed up with it:

SHOW SLAVE STATUS\G
*************************** 1. row ***************************
 [...]
             Master_Server_Id: 1
                  Master_UUID: 00013454-1111-1111-1111-111111111111
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more …