This is the fourth article in our series about MySQL NDB Cluster replication. We’ve now got so far into the details that data can not only be replicated from one cluster to the other but also back to the first again, we call this circular replication and it enables locating clusters in disparate places to […]

This post was originally published on the Percona Community blog.If you are in the world of application development, you know that every application has a lifecycle. An application lifecycle refers to the stages that our application goes through, from initial planning, building, deployment, monitoring, and maintenance in different environments where our application can be executed.On […]

Recently during the Swedish MySQL User Group (SMUG), I presented a session dedicated to MySQL InnoDB Primary Keys.

I forgot to mention a detail that many people are not aware, but Jeremy Cole has pointed out.

Primary Key always included in secondary indexes at the right-most column

When we define a secondary index, the secondary index includes the Primary Key as the right-most column of the index. It’s silently added, meaning that it’s not visible but it’s used to point back to the record in the clustered index.

This is an example with a table having a Primary Key composed of multiple columns:

CREATE TABLE `t1` (
`a` int NOT NULL,
`b` int NOT NULL, 
`c` int NOT NULL,
`d` int NOT NULL,
`e` int …

Our MySQL Belgian Days were a complete success. With 120 participants, the room was packed throughout the 2 days from the first to the last session. A record for this event ! The audience was made up of customers (some from very far away), users, contributors, community members and, of course, old friends. The atmosphere […]

Historically, MySQL does not require explicit primary key defined on tables, and it’s like that by default till this day (MySQL version 8.3.0). Such a requirement is imposed through two replication methods, though: Group Replication and Percona XtraDB Cluster (PXC), where using tables without a primary key is not allowed by default. There are many […]

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Disclaimer: The majority of examples in this post, are performed in a personal development/learning workstation environment and should not be considered production quality or ready. Your particular goals and needs may vary. Like always, just because …

To be honest, the comparison between the two MySQL distributions is not something that excited me a lot. Mainly because from my MySQL memories, I knew that there is not a real difference between the two distributions when talking about the code base.To my knowledge the differences in the enterprise version are in the additional […]

Are your MySQL users using ‘password’, ‘s3cr3t’, or ‘thebossisajerk’ as their passwords? Easy-to-guess passwords can be disastrous to the security of your data, but there is a way to exclude inappropriate words or phrases from being used. The first step is to compile a list of words and phrases you want to exclude, and that […]

This post goes through installing and configuring Ruby and Ruby on Rails for MySQL. The first step requires updating the Ubuntu OS:

sudo apt-get update

Interestingly, I found that the man-db service had inadvertently stopped. It raised the following error:

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. 

You run this command to find the problem with the dpkg utility:

sudo dpkg --configure -a

It returned:

Setting up man-db (2.10.2-1) ...
Updating database of manual pages ...
man-db.service is a disabled or a static unit not running, not starting it.

The following command started the man-db service:

sudo systemctl start man-db.service

Next, you install the prerequisite packages with this command:

sudo apt-get install -y git-core zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev …

FOSDEM is for sure one of the most respected free and open source software-focused conferences in Europe, which is loved by many, myself included. It is from the point of love I am raising concerns about transparency, which seems to be lacking in regard to some processes at FOSDEM.For many years, as long as I […]