As you may already know, there are many different places where a MySQL configuration variables can be initialized.

In MySQL 8.0, we added in performance_schema a table allowing you to easily find where a variable was defined.

Let’s check this in action with max_connections for example.

I started mysqld and now I check the value of max_connections:

mysql> show global variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 151   |
+-----------------+-------+

We can also use the performance.schema table called variables_info to get some more details about it:

mysql> SELECT t1.*, VARIABLE_VALUE 
       FROM performance_schema.variables_info t1 
       JOIN performance_schema.global_variables t2 
         ON t2.VARIABLE_NAME=t1.VARIABLE_NAME
      WHERE …

Join Shree Nair, Product Manager at Webyog, as he demonstrates the new features introduced in the recent Monyog releases and rolls out the roadmap for the upcoming releases.

Date & Time: Tuesday, Nov 21, 2017 at 11:00 am EDT / 5:00 pm CET.

Register Now!

What to expect from the webinar?

You will have a better understanding of how to use the new features per your use-case. You will learn about the product roadmap. You can take part in Q&A session and submit your feature requests too.

If you can’t attend this webinar live, register anyway and we’ll send you a link to the recording.

You can download a free trial of Monyog …

Announcing the opening of the Percona Live Open Source Database Conference 2018 in Santa Clara, CA, call for papers. It will be open from now until December  22, 2017.

Our theme is “Championing Open Source Databases,” with topics of MySQL, MongoDB and other open source databases, including PostgreSQL, time series databases and RocksDB. Sessions tracks include Developers, Operations and Business/Case Studies.

We’re looking forward to your submissions! We want proposals that cover the many aspects and current trends of using open source databases, including design practices, application development, performance optimization, HA and clustering, cloud, containers and new technologies, as well as new and …

As you probably already know, MySQL 8.0 supports Unicode 9.0 and our default charset moved from latin1 to utf8mb4.

Recently, Gabi (certainly working on an amazing presentation for PHPWorld) asked me something about how the client deals with the emojis while checking Morgo’s post about 8.0 RC1.

I didn’t know the answer and had to play with it, here is the outcome of these tests.

First let’s try to use the standard MySQL client and paste the dophin emoji from emojipedia:

SQLyog is a professional-grade GUI tool for the MySQL RDBMS. SQLyog is available for the Windows operating system starting from Windows XP/Windows 2003 to Windows 8/Server 2008 R2. It will also work under Linux, Unix and Mac OS X using the Wine environment. Moreover, a subset of SQLyog Enterprise/Ultimate functionalities are available with the free SQLyog Job Agent (SJA) for Linux as a native Linux utility. This makes it possible to specify and test ‘scheduled jobs’ on a Windows environment and port execution parameters seamlessly to a Linux environment.

Why Use a Database Administration Tool

Database administration tools provide a GUI/Web interface to automate database tasks like querying tables, find and replace operations, and any other task that you might want to run on a database. With respect to MySQL, it offers the free MySQL Workbench. Although it’s far more …

In MySQL 8.0.3, we have introduced a new optimizer hint called SET_VAR. This hint allows to change the value of a system variable for a single query.

Earlier, changing a system variable for a single query would require four steps:

1) Store current value.

…

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It is with great pleasure, I can announce that a new book dedicated to MySQL NDB Cluster has just been released. The book Pro MySQL NDB Cluster is written by my colleague Mikiya Okuno and myself and is a nearly 700 pages deep dive into the world of MySQL NDB Cluster. The book is published by Apress.

Tip: There are several ways to cluster MySQL. This book is about the product MySQL Cluster (often called MySQL NDB Cluster to clarify which cluster it is). There is also MySQL InnoDB Cluster, …

Join Percona Chief Evangelist Colin Charles as he covers happenings, gives pointers and provides musings on the open source database community.

We’re close to opening up the call for papers for Percona Live Santa Clara 2018 and I expect this to happen next week. We also have a committee all lined up and ready to vote on submissions.

In other news, I’ve spent some time preparing for the Korean MySQL Power Group meetup to be held in Seoul this Saturday, 11 November 2017. This is a great opportunity for us to extend our reach in Asia. This meetup gathers together top DBAs from Internet companies that use MySQL and related technologies.

Gartner has released their Magic Quadrant …

In this blog post, I’ll look at MySQL and Linux context switches and what is the normal number per second for a database environment.

You might have heard many times about the importance of looking at the number of context switches to indicate if MySQL is suffering from the internal contention issues. I often get the question of what is a “normal” or “acceptable” number, and at what point should you worry about the number of context switches per second?

First, let’s talk about what context switches are in Linux. This StackOverflow Thread provides a good discussion, with a lot of details, but basically it works like this:  

The process (or thread in MySQL’s case) is running its computations. Sooner or later, it has to do some blocking operation: disk IO, network IO, block waiting on a mutex …

Ok, so now we’re got our InnoDB Cluster a-clustering, MySQL Router a-routing, now we need some disaster to be a-disaster-recovering…

A foreword first.

If you’re looking to use Enterprise Backup to recover a single node and restore that node back into an existing InnoDB Cluster, LeFred takes you through that one nicely here.

Preparing for backup

On our single primary server, the one that allows write, which was ic2/10.0.0.12 in my case:

mysql -uroot -poracle << EOF 
SET sql_log_bin = OFF; 
 create user 'backup'@'%' identified by 'oracle';
 grant all on *.* to 'backup'@'%';
SET sql_log_bin = ON; 
EOF

Let’s create something to backup (if you haven’t already done so of course):

mysqlsh --uri …