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 …

As a principal architect at Percona, one of my duties is to tune MySQL database servers for our customers. The tuning effort looks at every aspect of the database service like the operating system, the MySQL configuration, the schema, the queries, etc. We have well-defined processes to tune the operating system and the MySQL configuration. However, tuning the schema and the queries using it can be anywhere from trivial to extremely challenging.

The challenge with the schema and the queries is mostly with the indexes. The most common types of indexes are based on b-trees or hash lists. InnoDB doesn’t support hash indexes, a bummer for equality conditions. B-tree indexes are more general-purpose, they are decent for equality conditions and very good for range conditions. They are however quite heavy and very dependent on the defined order of columns. They are also poor for double range conditions.

Double range conditions can be …

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, …

As you might know, mysqldump is single-threaded and STDOUT is its default output. As MyDumper is multithreaded, it has to write on different files. Since version 0.11.3 was released in Nov 2021, we have the possibility to stream our backup in MyDumper. We thought for several months until we decided what was the simplest way to implement it and we also had to add support for compression. So, after fixing several bugs, and we now consider it is stable enough, we can explain how it works.

How Can You Stream if MyDumper is Multithreaded?

Receiving a stream is not a problem for myloader, it receives a file at a time and sends it to a thread to process it. However, each worker thread in mydumper is connected to the database, and as soon as it reads data, it should be sent to the stream, which might cause collisions with other worker threads that are reading data from the database. In order to avoid this issue, we ended up with the …

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 …

The binary logging format in MySQL has been ROW by default since MySQL 5.7, yet there are still many users sticking with STATEMENT or MIXED formats for various reasons. In some cases, there is just simple hesitation from changing something that has worked for years on legacy applications. But in others, there may be serious blockers, most typically missing primary keys in badly designed schemas, which would lead to serious performance issues on the replicas.

As a Support Engineer, I can still see quite a few customers using STATEMENT or MIXED formats, even if they are already on MySQL 8.0. In many cases this is OK, but recently I had to deal with a pretty nasty case, where not using ROW format was found to cause the replicas to silently lose data updates, without raising any replication errors! Was it some really …

Last week at Percona Live, I was asked what book I recommend for novices seeking to learn MySQL.  For a long time, there has not been a good choice for modern versions of MySQL. Luckily I had just stumbled upon such a book.  Now I am happy to recommend The MySQL Workshop – A practical guide to working with data and managing databases with MySQL by Petit and Cosentino.

The first chapter introduces database architectures, data types, storage engines (including MyRocks), and data normalization. The following chapter cover in great detail how to create a database, using MySQL Workbench, backups & restoring data, and creating indexes. Chapter four has a very good section on working with SQL, functions, and case statements. Then JOINs and stored procedures are covered.

In another book, that would probably be enough content, but later chapters plunge into using Node.JS, Access, and Excel with MySQL. …

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 …

Oracle released MySQL Server 8.0.29 on April 26th and this is a quick review of the release notes.  I have put my own comments in italics.

So what is in the ’29 release of MySQL Server?  Does it come festooned with new, neat features or is it a big bug-fix bonanza?

The TL;DR

While this server release has some interesting stuff, there is no compelling feature that will necessitate an immediate upgrade.  Read through the release notes to see if anything in there that is a must for you but for most of us, MySQL 8.0.29 does not require an immediate update.  If this was a birthday or holiday present, ’29 is the equivalent of getting a fresh box of dental floss – useful but not thrilling.

The shell is evolving too and the new version for VS Code looks promising.

MySQL Server 8.0.29 UTF8MB3?

The server now makes extensive use of UTF8MB3 (yes 3, not …