In my talk at Percona Live 2021, “Creating Chaos in Databases”, I discussed how creating a controlled interruption in available resources (I used primary pod and network interruptions) allows us to test the stability of a database, and in our case, Percona XtraDB Cluster.

I also mentioned in the talk that my testing led to diagnosing a few unpleasant bugs, namely:

• PXC-3437: Node fails to join in the endless loop
• PXC-3580: Aggressive network outages on one node makes the whole cluster unusable
• …

We talk a lot about Galera Cluster for MySQL being great for High Availability, but what about Disaster Recovery (DR)? Database outages may occur when you lose a data centre due to power outages or natural disaster, so why not plan appropriately in advance?

In this webinar, we will discuss the business considerations including achieving the highest possible uptime, focus on business impact, risk mitigation, and disaster recovery itself. What scenarios are right for you: fully synchronous replication across various data centres? A mix of synchronous and asynchronous to an offsite location?

We will discuss Galera Cluster, mixed setups, the use of proxies, and also evaluate some third party solutions. We will debunk claims about how Galera Cluster might not work across data centers, tell you how to successfully do this across data centres, with performance tuning settings for all the segments. Galera 4 has also been released, making …

I recently learned of some odd behavior using MySQL BETWEEN operator queries, filtering by a DATETIME column. I wrote about this over on Medium so I am sharing the post for any readers here who are interested…

Image by _Alicja_ from Pixabay 

Self-Promotion:

If you enjoy the content written here, by all means, share this blog and your favorite post(s) with others who may benefit …

The students needed yet another example of LEFT JOIN, RIGHT JOIN, and FULL JOIN syntax (by combining a left and right join with the UNION set operator). To that end, I put this set of examples together.

The example also shows how to order the result set from a derived table with the UNION operator. It uses the WITH clause to build a Common Table Expression (CTE), which allows the query to order the UNION set operator’s product based on the left and right join queries. It uses a CASE statement to order the result sets. The left_table is the parent table and the right_table is the child table in the relationship, which means the right_table holds a left_id foreign key column that lets you connect matching rows in the left_table.

You build the little model with the following …

When organizing things helps to simplify life.

In the previous article, we start to explore dynamic privileges and the interaction with static ones. We also saw how to remove SUPER privilege from a DBA account. 

What we did was go by subtraction. But in real life, we should act differently. We should ADD only what is really needed for the account to work correctly.

Adding privilege one by one, and for each user is problematic given the level of interaction they may have, and also prone to mistakes. 

Instead, we can use ROLES to group, assign, and revoke the correct privileges in a much easier way.

This is becoming even more important in MySQL with the advent of dynamic privileges.

What should we do to correctly use ROLES? Well first of all design.   …

When trying to make things better, make our life very complicated.

I was working on a Security Threat Tool script, when I had to learn more about the interaction between static and dynamic privileges in MySQL 8.

Dynamic privileges is a “new” thing added in MySQL 8 to easily extend the privileges definition, and at the same time to provide more granularity. For instance the FLUSH operation now has dedicated Privileges and by scope. 

Dynamic privileges are assigned at runtime. Most of them are active when the server starts. But they can also change in respect to the components or plugin when activated. (https://dev.mysql.com/doc/mysql-security-excerpt/8.0/en/privileges-provided.html#privileges-provided-dynamic)

Static privileges are the classical privileges available in MySQL …

When trying to make things better, make it very complicated.

I was working on a Security Threat Tool script when I had to learn more about the interaction between static and dynamic privileges in MySQL 8.

Dynamic privileges is a “new” thing added in MySQL 8 to easily extend the privileges definition, and at the same time to provide more granularity. For instance, the FLUSH operation now has dedicated Privileges and by scope. 

Dynamic privileges are assigned at runtime. Most of them are active when the server starts. But they can also change with respect to the components or plugin when activated. ( …

When organizing things helps to simplify life.

In the previous article we start to explore dynamic privileges and the interaction with the static ones. We also saw how to remove SUPER privilege from a DBA account. 

What we did was go by subtraction. But in real life, we should act differently. We should ADD only what is really needed for the account to work correctly.

Adding privilege one by one, and for each user is problematic given the level of interaction they may have, and also prone to mistakes. 

Instead we can use ROLES to group, assign and revoke the correct privileges in a much easier way.

This is becoming even more important in MySQL with the advent of dynamic privileges.

What should we do to correctly use ROLEs? Well first of all …

The practice of running databases in containers continues to grow in popularity.  As a Technical Account Manager at Percona, I get asked regularly about our Percona Distribution for MySQL Operator.  Additionally, I’m asked what I’m seeing in the industry in terms of adoption.  In most cases, the questions stem around new deployments.  Our DBaaS tool (currently in Technical Preview) makes launching a new cluster in a Kubernetes deployment trivial.  

Once the operator completes and verifies the setup, the UI displays the endpoint and credentials and you are on your way.  Voila!  You now have a cluster, behind a load balancer, that you can access from within your k8s cluster or …

One of the most popular ways in achieving high availability for MySQL is replication. Replication has been around for many years, and became much more stable with the introduction of GTIDs. But even with these improvements, the replication process can break due to various reasons - for instance, when master and slave are out of sync because writes were sent directly to the slave. How do you troubleshoot replication issues, and how do you fix them? 

In this blog post, we will discuss some of the common issues with replication and how to fix them with ClusterControl. Let’s start with the first one.

Replication Stopped With Some Error

Most MySQL DBAs will typically see this kind of problem at least once …