Since 8.0.30, you have the possibility to modify the InnoDB Redo Log Capacity online. An undersized Redo Log Capacity is problematic and lead to performance issues.

However, it’s not recommended to oversize the Redo Log either. Redo Log files consume disk space and increases the recovery time in case of a restart (innodb_fast_shutdown=1) or a sudden crash. And it also slows down shutdown when innodb_fast_shutdown=0.

This means that now, you don’t need to restart MySQL if you want to increase or decrease the size of the InnoDB Redo Logs files. In fact, we don’t talk anymore about file size but about capacity ! The DBA doesn’t need to specify any file size and/or amount of files for Redo Logs anymore …

During my summer holidays, we released MySQL 8.0.30.

MySQL 8.0.30 was released on July 26th 2022. If you are using 8.0.29, it’s highly recommended to upgrade as there was a bug corrupting InnoDB files in a rare and specific case.

This new release contains several contributions from our awesome Community and on behalf of the entire MySQL Team, as usual, I would like to thanks all our contributors !

This new release contains patches from Facebook/Meta, Marcelo Altmann (Percona), Mengchu Shi, Zhou Xinjing (Tencent), Yuxiang Jiang (Tencent), Namrata Bhave, Hongyuan Li, Alexey Kopytov, Wei Zhao, Piotr Jurkiewicz, Dennis Gao, Zheng Lai, Bin Wang, Hao Wu (Tencent), Weijie Wu and Rahul Malik (Percona).

Once again, thank you all for your great contributions and to the companies you are working for.

…

Usually, I receive a lot of emails, and sometimes I read them on my phone and then… I forgot about them.. (shame on me).

On my Linux desktop, I used to use Get Things Gnome for a long time, due to the declining appeal of the project and the end of the extension for Thunderbird, I found it less and less useful.

I was then looking for a solution to have my todolist accessible from everywhere and that I could manage it myself, not hosted somewhere.

I found a very nice, fast and practical project that was easy to deploy and was using MySQL as backend: myTinyTodo.

However, I was missing the possibility to easily create a new task from an email (and especially on my phone).

This is why I decided to write a script that would perform exactly what I was looking for and integrated …

If you write C applications that need to connect to MySQL, you can use the MySQL C API aka libmysqlclient. The MySQL C API replaces the outdated MySQL-Connector-C.

If you want to use MySQL 8.0 as a Document Store with the X Protocol, you need then to use MySQL Connector/C++ 8.0.

Some have asked how to compile only the MySQL C API.

Compiling only libmysqlclient

As the FAQ stipulates it, it’s not possible to only build the library. However, as mentioned in the documentation, it’s possible to reduce the amount of compiled products with some …

When performing physical backup on system that are heavily used, it can happen that the backup speed cannot keep up with the redo log generation. This can happen when the backup storage is slower than the redo log storage media and this can lead in inconsistency in the generated backup.

MySQL Enterprise Backup (aka MEB) and probably Percona Xtrabackup, benefit from the possibility to sequentially write redo log records to an archive file in addition to the redo log files.

This feature was introduced in MySQL 8.0.17.

How to enable it ?

To enable this feature, two settings are necessary:

• set globally a directory where those archiving logs can be stored
• start the archiving process in a session by calling a dedicated function

The global variable is …

Full table scans can be problematic for performance. Certainly if the scanned tables are large. The worst case is when full table scans are involved in joins and particularly when the scanned table is not the first one (this was dramatic before MySQL 8.0 as Block Nested Loop was used) !

A full table scans means that MySQL was not able to use an index (no index or no filters using it).

Effects

When Full Table Scans happen (depending of the size of course), a lot of data gets pulled into the Buffer Pool and maybe other important data from the working set is pulled out. Most of the time that new data in the Buffer Pool might even not be required by the application, what a waste of resources !

You then understand that another side effect of Full Table Scans is the increase of I/O operations.

The most noticeable symptoms of Full Table Scans are:

• increase of CPU usage
• increase of …

Today, the book I would like to recommend is Efficient MySQL Performance – Best Practices and Techniques, Daniel Nichter, O’Reilly, 2021.

I participated (just a bit) in the writing of this book as technical reviewer with Vadim and Fipar. I really enjoyed that role of carefully reading the early drafts of the chapters Daniel was writing.

Although Daniel says the book is not for the experts, I think even experts will enjoy it because several key InnoDB concepts are also covered. You can see that I refer to the book often in my A graph a day, keeps the doctor away ! series on monitoring and trending.

If you’re looking for information on transaction isolation and undo logs, fuzzy checkpointing, etc… you’ll find …

This is the second article of the series dedicated to MySQL trending.

As I wrote before, understanding your workload and seeing the evolution of it over time can help anticipating problems and work on solutions before the breakdown.

This article covers MySQL History List Length also known as HLL.

MySQL History List is related to InnoDB Undo Logs. InnoDB is a multi-version storage engine (MVCC). It keeps information about old versions of changed rows to support transactional features such as concurrency and rollback. This information is stored in undo tablespaces in a data structure called a rollback segment.

This means that you can start a transaction and continue to see a consistent snapshot even if the data changed by other transaction. This behavior is related to the …

In a previous post, I explained how you can collect and plot metrics using MySQL Shell.

This is a new series of article where I will explain how to read and understand some of the generated graphs.

Understanding your workload and seeing the evolution of it over time can help anticipating problems and work on solutions before the breakdown.

Let’s start the series with a concept that is not always well understood or at least not always considered at its true value: MySQL Checkpoint Age.

example of checkpoint age graphInnoDB Checkpointing

Before analyzing the graph, we need to understand what is MySQL InnoDB Checkpointing.

Each change to a data page in the InnoDB Buffer Pool are also written into the Write Ahead Logs.

In the literature they are sometimes called Transaction …

When it’s time for a new MySQL release, it’s also time to thank our contributors !

Released on April 26th, MySQL 8.0.29 contains several contributions from our awesome Community and on behalf of the entire MySQL Team, I would like to thank you all !

This new releases contains patches from Vilnis Termanis, Luke Weber, Meik Milevczik, Song Zhibai, Zheng Lai, Øystein Grøvlen, Facebook, Biran Yue, Hope Lee, Rahul Malik, Christopher Chavez, Chen Yi, Ning PeiPei, Jianjian Song, Jack Wotherspon and Bin Wang.

Once again, thank you all for your great contributions and to the company you are working for.

Here is the list of the above contributions and related bugs:

Clients / Connectors

• #81519 Connector/Python: Guarantee file closing of input files in optionfiles module – Vilnis Termanis
…