Introduction/FAQ

Question: I need to run a production-grade open source MySQL DB.

Answer: Percona to the rescue! Percona XtraDB Cluster (PXC) is an open source enterprise MySQL solution that helps you to ensure data availability for your applications while improving security and simplifying the development of new applications in the most demanding public, private, and hybrid cloud environments

Question: I forgot to mention that I need to run it on Kubernetes.

Answer: Percona to the rescue again! Percona Distribution for MySQL Operator based on Percona XtraDB Cluster contains everything you need to quickly and consistently deploy and scale Percona XtraDB …

When we run a SELECT in a replica server and it returns a different result to the one we would have obtained had we queried the source server instead, due to changes in the dataset that have not yet been replicated or synchronized to the replica, we get what is known as a stale read. My colleague Marcelo has blogged about Stale Reads and How to Fix Them before.

The need to avoid stale reads is a constraint that leads people into migrating to Percona XtraDB Cluster (PXC) / Galera Cluster or, more recently, Group Replication. I am focusing on PXC and Galera in this short blog post, which, similar to Group Replication, implements not exactly a synchronous replication model but what is commonly referred to as a …

Oracle’s MySQL 8.0.29 release extended the support for ALTER TABLE … ALGORITHM=INSTANT to 1) allow users to instantly add columns in any position of the table, and 2) instantly drop columns. As part of this work, the InnoDB redo log format has changed for all DML operations on the server. This new redo log format introduced a design flaw that can cause data corruption for tables with INSTANT ADD/DROP COLUMNS.

The corruption happens when InnoDB crash recovery takes place. InnoDB applies redo logs at startup. Percona XtraBackup copies the redo log during backup and applies it as part of the –prepare step to bring the backup to a consistent state.

Percona fixed the corruption issue and several other issues with the INSTANT ADD/DROP column …

In this blog post, I will show how to install the MySQL-compatible Percona XtraDB Cluster (PXC) Operator on Minikube as well as perform some basic actions.   I am by no means a Kubernetes expert and this blog post is the result of my explorations preparing for a local MySQL Meetup, so if you have some comments or suggestions on how to do things better, please comment away!

For my experiments, I used Minikube version 1.26 with the docker driver in the most basic installation on Ubuntu 22.04 LTS, though it should work with other combinations, too. You also can find the official “Running Percona XtraDB Cluster on Minikube” documentation …

In this blog, I will demonstrate how to use Percona Monitoring and Management (PMM) to find out the reason why the MySQL server is stalling. I will use only one typical situation for the MySQL server stall in this example, but the same dashboards, graphs, and principles will help you in all other cases.

Nobody wants it but database servers may stop handling connections at some point. As a result, the application will slow down and then will stop responding.

It is always better to know about the stall from a monitoring instrument rather than from your own customers.

PMM is a great help in this case. If you look at its graphs and notice that many of them started showing unusual behavior, you need to react. In the case of stalls, you will see that either some activity went to 0 or, otherwise, it increased to high …

There are two Operators at Percona to deploy MySQL on Kubernetes:

• one is based on Percona XtraDB Cluster (PXC), production-ready and widely adopted
• another is based on Percona Server for MySQL, now in tech preview and not recommended for production yet

We wrote a blog post in the past explaining the thought process and reasoning behind creating the new Operator for MySQL. The goal for us is to provide production-grade solutions to run MySQL in Kubernetes and support various replication configurations:

• Synchronous replication
  …

Percona Server for MySQL 8.0.28-20 introduces a new keyring component, component_keyring_kms, which allows using the AWS Key Management Service as a keyring. The component is also included in Percona XtraBackup 8.0.28, allowing backing up databases encrypted with this component.

The feature is similar to the AWS keyring plugin included in MySQL Enterprise, but it is implemented as a component instead, and because of that, it requires a different configuration.

Configuring AWS KMS

The component uses a single Master Key on KMS, which has to be created manually before configuring the component. This key can also be changed later, and existing keys using the old key will remain usable, as long as the key still exists …

Imagine you need to design an online system for storing documents on a per-user basis where nobody, including database administrators, would be able to change the content of those documents without being noticed by document owners.

In Percona Server for MySQL 8.0.28-20, we added a new component called Encryption UDFs – an open-source alternative to MySQL Enterprise Encryption that allows users to access a number of low-level OpenSSL encryption primitives directly from MySQL. This includes calculating digests (with a great variety of hash functions), asymmetric key generation (RSA, …

Temporary Tables handling in MySQL has a somewhat checkered past. Some time ago, my colleague Przemek wrote a post about differences in the implementations between versions of MySQL. If you are looking for the differences in implementation, that’s a perfect place to check.

In this post, I’d like to focus on Session Temporary Tablespaces, InnoDB on-disk internal temporary tables that come to play when a query requires storing more data than tmp_table_size or TempTable engine allocated more than …

MySQL allows changing the location of the general log and the slow query log while the server is running by anybody having the SYSTEM_VARIABLES_ADMIN privilege to any location, including appending to existing files. In Percona Server for MySQL 8.0.28-19 we introduced a new system variable, secure-log-path, that can be used to restrict the location of these log files to avoid accidents or possible data corruption attacks.

When somebody with the system variables admin privilege changes these variables, the server runs a few sanity checks. Unfortunately, these checks are quite minimal, and only verify that the specified file is writable by mysqld.

Compared to this, other variables specifying write-related file and directory names are either read-only during the runtime of the server (such as datadir, tmpdir, or log_error), or have additional …