The latest from the MySQL community

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 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 …

This post explains the inherent problem of running online schema changes in MySQL, on tables participating in a foreign key relationship. We'll lay some ground rules and facts, sketch a simplified schema, and dive into an online schema change operation. Our discussion applies to gh-ost, pt-online-schema-change, and VReplication based migrations, or any other online schema change tool that works with a shadow/ghost table like the Facebook tools. Why Online DDL? # Online schema change tools come as workarounds to an old problem: schema migrations in MySQL were blocking, uninterruptible, aggressive in resources, replication unfriendly.

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 …

In the previous release of our Percona Distribution for MySQL Operator, we implemented one interesting feature, which can be seen as “self-healing”: https://jira.percona.com/browse/K8SPXC-564.

I do not think it got enough attention, so I want to write more about this.

As it is well known, a 3-node cluster can survive a crash of one node (or pod, in Kubernetes terminology), and this case is very well handled by itself. However, if there is a problem with 2 nodes at the same time, this scenario is problematic for Percona XtraDB Cluster. Let’s see why this is a problem.

First, let’s review if the first node goes offline:

In this case, the cluster can continue work, because Node 1 and Node 2 figure out …