While I was working on my grFailOver POC, I have also done some additional parallel testing. One of them was to see how online DDL is executed inside a Group Replication cluster.

The online DDL feature provides support for instant and in-place table alterations and concurrent DML. Checking the Group Replication (GR) official documentation, I was trying to identify if any limitation exists, but the only thing I have found was this:

“Concurrent DDL versus DML Operations.  Concurrent data definition statements and data manipulation statements executing against the same object but on different servers is not supported when using multi-primary mode. During execution of Data Definition Language (DDL) statements on an object, executing concurrent Data Manipulation Language (DML) on the …

As database footprints continue to explode, many companies are looking for ways to deal with such rapid growth.  One approach is to refactor traditional relational databases to fit into a NoSQL engine, where horizontal scalability is easier.  However, in many cases, this is in no way a trivial undertaking.

Another approach that has been gaining interest is the use of MyRocks as an alternative storage engine to the traditional InnoDB.  While not for everyone, in certain use cases it could be a potential solution.  As with so many things open source, the next standard questions are: which version should I use?  Any differences with the engine if I use MyRocks with MySQL 5.7 vs 8.0?

In this post, I wanted to touch on this and give some high-level thoughts on MyRocks when it comes to the version of MySQL.

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Percona Technical Account Managers get the privilege of working with some of our largest enterprise clients day in and day out.  As such, we get to really focus on how to best leverage our technology to generate measurable benefits for our users.  While it is fun to “nerd out” and always strive to use the latest and greatest, we need to stay focused on demonstrating business value and a genuine need.  Over the past few months, I’ve been working with one of my larger clients, Dropbox, along with our professional services team to validate the use of Percona Server for MySQL with the MyRocks storage engine over a large portion of their MySQL infrastructure.

Please note – this is not meant to be a deep dive into the technical details around …

Lately, the number of questions about how to build Percona software has been increased. More and more people try to add their own patches, add some modifications, and build software by themselves. But this raises the question of how to do this in the same way as Percona does, as sometimes the compiler flag can make a drastic impact on the final binary.

First of all, let’s talk about the stages of compiling software.

I would say that at the beginning you need to prepare the build environment, install all the needed dependencies, and so on. For each version, the dependency list would be different. How do you get the correct dependency list? You can get all build requirements from the spec file (on rpm-based systems) or from the control file( on deb-based systems).

The next stage is to get the source code of Percona …

MySQL 5.7, alongside other many improvements, brought bulk load for creating an index (WL#7277 to be specific), which made ADD INDEX operations much faster by disabling redo logging and making the changes directly to tablespace files. This change requires extra care for backup tools. To block DDL statements on an instance, Percona Server for MySQL implemented LOCK TABLES FOR BACKUP. Percona XtraBackup (PXB) uses this lock for the duration of the backup. This lock does not affect DML statements.

MySQL 5.7 doesn’t have an option to block an instance against DDL and to allow all MDL’s. Thus, Percona XtraBackup has also implemented –lock-ddl-per-table. Before we go into other details, let’s understand how –lock-ddl-per-table works up to now:

1. PXB …

Changing the default value (3) of log_error_verbosity in MySQL/Percona Server for MySQL 5.7 can have a hidden unintended effect! What does log_error_verbosity do exactly? As per the documentation:

“The log_error_verbosity system variable specifies the verbosity for handling events intended for the error log.“

Basically a value of 1 logs only [Errors]; 2 is 1)+[Warnings]; and 3 is 2)+[Notes].

For example, one might be tempted to change the default of log_error_verbosity since the error.log might be bloated with thousands (or millions) of lines with [Notes], such as:

2020-10-08T17:02:56.736179Z 3 [Note] Access denied for user 'root'@'localhost' (using password: NO)
2020-10-08T17:04:48.149038Z 4 [Note] Aborted connection 4 to db: 'unconnected' user: 'root' host: 'localhost' (Got timeout reading communication packets)

(P.S. you can read more about those Notes on this other Percona blog posts):

MySQL 8.0 General Availability release was launched in April 2018, and since then there have been ten versions of MySQL 8 and Percona Server for MySQL released. The MySQL Community expressed a high opinion of the MySQL 8.0 advantages, so a lot of databases have been successfully upgraded to the new version. But many of them still need to be up to date.

Percona has prepared a free course “How to Upgrade to MySQL 8.0” that helps you with this task.

It is a series of useful videos for 3-4 minutes. At the end of the course, you can pass the QUIZ and get a certificate. 

Follow the link to take the course:  https://classroom.google.com/c/MTM2MDIyNDIzMDQy?cjc=zjsst4l

You can also join the course manually. Just open Google Classroom and click “Join class” and enter the code of the class “zjsst4l”. …

We are excited to let you know about two upcoming changes to Percona XtraBackup which will align Percona XtraBackup Versions with Percona Server for MySQL.  These changes are to bring Percona XtraBackup release naming line with Percona Server and MySQL and ensure Percona XtraBackup executes complete backups.

The first is a change to the naming structure of releases.  This change is something we believe will help when working with Percona products and is designed to position Percona XtraBackup to be in sync with the current release naming strategy of Percona Server for MySQL and Percona XtraDB Cluster.

The current naming structure of …

Disclaimer: the following script only works for Percona Server for MySQL 5.7, and relies on enabling performance schema (PS) instrumentation which can add overhead on high concurrent systems, and is not intended for continuous production usage as it’s a POC (proof of concept).

Introduction

In Percona Support, we frequently receive tickets related to deadlocks and even though the deadlock concept is simple, troubleshooting might not be in all cases. 

As explained in How to Deal with MySQL Deadlocks, a deadlock occurs when two or more transactions mutually hold and request for locks, creating a cycle of dependencies. MySQL will detect deadlocks and kill one of the transactions (making it rollback), and the deadlock will be printed in SEIS (show engine innodb status). Limitations of using this approach …

Recently I had the opportunity to test a storage device from ScaleFlux called CSD 2000. In this blog post, I will share the results of using it to run MySQL in comparison with an Intel device that had a similar capacity.

First of all, why do we need another storage device? Why is ScaleFlux any different?

The answer is simple; it gives us built-in compression and atomic writes. For many workloads, but especially for database-type workloads, these are very important features.

Because of built-in compression, we can store more data on the ScaleFlux device than on a similar device with the same capacity.

Because of atomic writes, we can disable InnoDB Double Write buffer which means less writes/fsync on the disk layer. This should give us a performance advantage against non-atomic drives.

I ran many different tests on different data sizes, with different …