We’ve already discussed using the ORDER BY clause with subqueries. You can also, however, use the 

ORDER BY

 clause with sorting results of one of the columns. Actually, this is most common way to use this clause.

Sometimes such queries require using temporary tables or filesort, and a regular

EXPLAIN

  clause provides this information. But it doesn’t show if this job is needed for

ORDER BY

 or for optimizing another part of the query.

For example, if we take a pretty simple query ( 

select distinct last_name from employees order by last_name asc

) and run

EXPLAIN

  on it, we can see that both the …

It is not new that we can store a JSON content in a normal table text field. This has always been the case in the past. But two key features were missing : filtering based on JSON content attributes and indexing of the JSON content. With MariaDB 10.1 CONNECT storage Engine we offer support for ...continue reading "MariaDB JSON text indexing"

There is a growing interest in Apache Spark, so I wanted to play with it (especially after Alexander Rubin’s Using Apache Spark post).

To start, I used the recently released Apache Spark 1.6.0 for this experiment, and I will play with “Airlines On-Time Performance” database from
http://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=236&DB_Short_Name=On-Time. You can find the scripts I used here https://github.com/Percona-Lab/ontime-airline-performance. The uncompressed dataset …

In MySQL for Visual Studio version 1.2.4 and earlier, there was an issue, existing only under a specific scenario, which was preventing the plugin to be uninstalled (either using the “Remove” option in the Windows Control Panel/Programs, or the MySQL Installer for Windows) or upgraded to a newer version, causing the uninstall/update action to be rolled back during the process. (For further information about this issue please refer to http://bugs.mysql.com/bug.php?id=71226).

Such scenario can be achieved as follows:

1. First install Visual Studio 2012, or VS 2013 or VS 2015
2. Then, install MySQL for Visual Studio version 1.2.4 or earlier
3. Later, uninstall Visual Studio 2012, or VS2013 or VS2015

With the scenario described above, the uninstall/upgrade process of the MySQL for Visual Studio plugin is …

The MySQL Windows Experience Team is proud to announce the release of MySQL for Visual Studio 1.2.6. This is a maintenance release for 1.2.x. It can be used for production environments.

MySQL for Visual Studio is a product that includes all of the Visual Studio integration functionality to create and manage MySQL databases when developing .NET applications.

MySQL for Visual Studio is installed using the MySQL Installer for Windows which comes in 2 versions:

• Full (150 MB) which includes a complete set of MySQL products with their binaries included in the downloaded bundle.
• Web (1.5 MB – a network install) which will just pull MySQL for Visual Studio over the web and install it when run.

You can download MySQL Installer from our …

You may not be aware that the mechanism used to fingerprint the SSL certificates that  keep your access to websites encrypted and secure is changing. The old method, known as SHA1 is being deprecated – meaning it will no longer be supported. As per January 2016 various vendors will no longer support creating certificates with SHA1, and browsers show warnings when they encounter an old SHA1 certificate. Per January 2017 browsers will reject old certificates.

The new signing method, known as SHA2, has been available for some time. Users have had a choice of signing methods up until now, but there are still many sites using old certificates out there. You may want to check the security on any SSL websites you own or run!

To ensure your users’ security and privacy, force https across your entire website, not just e-commerce or other sections. You may have noticed this move on major websites over the last …

In this article we will show you how to install GLPI with Apache, PHP and MySQL on a Debian 7 VPS. GLPI is an IT software management package developed in PHP. It offers many functionalities one of which is to build up a database with an inventory for your company (computer, monitors, software, printers…). GLPI has enhanced functions to make the daily life for the administrators easier, like a job-tracking-system with mail-notification and methods to build a database with basic information about your network-topology. Below are the functions of this application: Inventory of computers, peripherals, network printers and associated components […]

What better way to learn the basics of MySQL Performance Troubleshooting, than by observing a MySQL expert troubleshoot a nasty MySQL 5.7 performance bug, that a team of DBAs were chasing for weeks before giving up and calling in an external consultant for help.

The bug was causing roughly 2 minute long lock-ups for all MySQL write queries at seemingly random 20-30 hour intervals and it took me (the external consultant) only 4 hours to uncover the issue (and a couple more to find and showcase a solution).

Once upon a time…

Wait. Before we start with the story, I would like to share a couple of basic principles I obey when troubleshooting. A lot of this applies to troubleshooting other types of systems too, but since you’re here for MySQL, let’s focus on that.

First of all, as you may already know from my earlier posts, I am a big fan of a …

In MySQL 5.7.8 we added support for version tokens. This is a new feature that enables you to prevent accessing incorrect or out-of-date data, and stray modifications executing on the wrong server.

For some backstory

When there are multiple MySQL instances running on a Linux machine, there is a reasonable chance that clients could connect to the wrong instance.…

In the previous EXPLAIN FORMAT=JSON is Cool! series blog post, we discussed the  

group_by_subqueries

  member (which is child of

grouping_operation

). Let’s now focus on the 

grouping_operation

  and other details of 

GROUP BY

  processing.

grouping_operation

 simply shows the details of what happens when the 

GROUP BY

 clause is run:

mysql> explain format=json …