The latest from the MySQL community

What is a median value?

The median of an array of numbers is the value of the middle item in the array, assuming the array is sorted. If the array has an even number of items, the median represents the average of the two middle values in the array.

This value is very popular one tries to understand “in which half my value is?”. For example, I got a D (or 80) in my last test at school, am I in the top 50% of my class students or not?

As a practical example, let’s look into the process of retrieving the median value from the following array of school test grades: [55, 80, 95, 100, 99, 70, 60].

1. First, we’ll sort the array: [55, 80, 95, 100, 99, 70, 60]  ===> [55, 60, 70, 80, 95, 99, 100].
2. The array contains 7 items, which isn’t an even number, so therefore the median is the (7 / 2 + 1) item, which is the 4th item => 80.

Calculating the median value of …

This edition of Log Buffer covers Cloud, Oracle, SQL Server and MySQL and much more.

Cloud:

Introducing managed SSL for Google App Engine

Using Cloud Foundry CUPS to inject Spring Security credentials into a Spring Boot Application

ClusterControl in the Cloud – All Our Resources

Monitoring Amazon Aurora Audit Events with Amazon CloudWatch

Integrating Teradata with Amazon …

We are happy to announce that MySQL team is part of the OpenSource Lisbon 2017 as Gold sponsor. You can find our experts at the booth in expo area as well as you can listen the MySQL talk on Oracle MySQL: "How are you doing?" given by Mario Beck, the MySQL Sales Consulting Manager for EMEA. Mark your calendars for September 28, 2017 for OS Lisbon 2017!!! See more details at OS Lisbon 2017.

In this blog post, we talk about the results of Percona’s time series database poll “What Database Engine Are You Using to Store Time Series Data?”

Time series data is some of the most actionable data available when it comes to analyzing trends and making predictions. Simply put, time series data is data that is indexed not just by value, but by time as well – allowing you to view value changes over time as they occur. Obvious uses include the stock market, web traffic, user behavior, etc.

With the increasing number of smart devices in the Internet of Things (IoT), being able to track data over time is more and more important. With time series data, you can measure and make …

This post is the third of a series focusing on the MySQL high availability solutions available in 2017.

The first post looked at the elders, the technologies that have been around for more than ten years. The second post talked about the adults, the more recent and mature technologies. In this post, we will look at the emerging MySQL high availability solutions. The “baby” MySQL high availability solutions I chose for the blog are group replication, proxies and distributed storage.

Group replication

Group replication is the Oracle response to Galera. The term “InnoDB cluster” means a cluster using group replication. The goal is offering …

Sync MySQL Servers with ProxySQL Cluster

In the two previous blog posts about ProxySQL Cluster we described how to setup a Cluster, how to add users/rules and propagate them across the Cluster, how to provision new nodes, how to re-sync nodes after they have been out of the Cluster, and some features in the roadmap, especially around the concept of core nodes vs satellite nodes.
We also mention that there are 4 modules/tables that currently ProxySQL Cluster is able to sync:

• mysql_query_rules
• mysql_servers
• mysql_users
• proxysql_servers

We covered 3 of these, and the last one missing is how to sync mysql_servers, related to MySQL …

Notes/errata/updates for Chapter 3:
See the official book errata at http://tahaghoghi.com/LearningMySQL/errata.php – Chapter 3 includes pages 95 – 106.

On p. 96 – 97, there is an example of what you will see with SHOW DATABASES; You will likely also see sys, INFORMATION_SCHEMA and PERFORMANCE_SCHEMA databases.

On p. 97, it says “There are some restrictions on what characters and words you can use in your database, table and other names.” These days, it is possible to escape characters and reserved words, but it is still not recommended.

On p. 101-102, there are examples of how to run the MySQL monitor in “batch mode”. It says you can use either “SOURCE” or the redirection operator on commandline (

As continue of the previous blog posted on Aug 17, 2017, please find below a list conferences & events where you can find MySQL Community team or MySQL experts during the period of second half of September till end of December. The ones which are new are marked below. Please be aware that the list does not have to be final and during the time more events could be added or some of them removed. 

NA&LAD

• Madison PHP, Madison, US, Sep 22-23, 2017​

  • MySQL Community team is supporting this PHP conference as Community partner.
• Oracle Open …

A MySQL replication topology can be very complex (never underestimate a DBA’s creativity). But it’s very frequent to use an asynchronous slave from your primary database to run reporting or logical backup… or any kind of read workload you need. It can also be used as delay slave for data restore purpose.

Once you decided to provide HA to your primary database by migrating to MySQL InnoDB Cluster, you can of course still need and use one or more asynchronous slaves.

You have then an architecture that looks like this :

So as you can notice, your asynchronous slave needs to pick one of the members of the cluster as master. However when this node that act as master crashes (or is stopped for maintenance) what’s happening ?

…

Hello again! On August 16, we delivered a webinar on MySQL backups. As always, we’ve had a number of interesting questions. Some of them we’ve answered on the webinar, but we’d like to share some of them here in writing.

What is the best way to maintain daily full backups, but selective restores omitting certain archive tables?

There are several ways this can be done, listed below (though not necessarily limited to the following):

1. Using logical dumps (i.e., mydumper, mysqlpump, mysqldump). This allows you to dump per table and thus be able to selectively restore.
2. Backup the important tables and archive tables separately, allowing to restore separately as well. This is a better …