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745 blog posts in 13 categories

Using NGINX as a Database Load Balancer for Galera Cluster

Nginx is well-known for its ability to act as a reverse-proxy with small memory footprint. It usually sits in the front-end web tier to redirect connections to available backend services, provided these passed some health checks. Using a reverse-proxy is common when you are running a critical application or service that requires high availability. It also distributes the load equally among the backend services.

Understanding the MySQL Galera Cluster and MariaDB Cluster Diagnostic Logs

In a Galera cluster, whether you use MariaDB Cluster, Percona XtraDB Cluster or the Codership build, the MySQL error log is even more important. It gives you the same information as MySQL would, but you’ll also find in it information about Galera internals and replication. This data is crucial to understand the state of your cluster and to identify any issues which may impact the cluster’s ability to operate. In this post, we’ll try to make the Galera error log easier to understand.

Webinar Replay: Deploying MongoDB, MySQL, PostgreSQL & MariaDB’s MaxScale in 40min

Thanks to everyone who joined us for our recent live webinar on ‘ClusterControl 1.2.11 - new release’ led by Art van Scheppingen , Senior Support Engineer at Severalnines. The replay and slides to the webinar are now available to watch and read online.

wtmp Log Rotation Settings for Sudo User in ClusterControl

ClusterControl requires a super-privileged SSH user to provision database nodes. If you are running as non-root user, the corresponding user must able to execute sudo commands with or without sudo password. Unfortunately, this could generate another issue where performing remote command with “sudo” requires an interactive session (tty).

Understanding the MySQL Error Log

We are yet to see a software that runs perfectly, without any issues. MySQL is no exception there. It’s not the software’s fault - we need to be clear about that. We use MySQL in different places, on different hardware and within different environments. It’s also highly configurable. All those features make it great product but they come with a price - sometimes some settings won’t work correctly under certain conditions.

A Guide to MySQL User Management

In this example we will look at how you can use ClusterControl to create a user and assign privileges to the user. We will create a user that has enough privileges to perform an xtrabackup.

Updating Your MySQL Configuration

Requires ClusterControl 1.2.11 or later. Applies to MySQL based clusters. From time to time it is necessary to tune and update your configuration. Here we will show you how you can change/update  individual parameters using the ClusterControl UI. Navigate to Manage > Configurations.

Optimizer Hints for Faster MySQL Query Execution

MySQL uses a cost-based optimizer to determine the best way to execute a query. It usually does a great job, but not all the time. There are different reasons for that. In some cases, it might not have enough information about the data and plan queries in a non-optimal way.

Severalnines’ Vinay Joosery Named UK Top 50 Data Leader & Influencer

Information Age today unveiled the inaugural list of the UK’s top 50 data leaders and influencers. “Very strong on product and technical development of open-source databases, Vinay has helped global and UK businesses like BT, AutoTrader Group and Ping Identity to scale, manage and develop (data) cloud operations.” - as just announced by Information Age.

Using Explain to Improve SQL Query Performance

When it comes to the query tuning, EXPLAIN is one the most important tool in the DBA’s arsenal. Why is a given query slow, what does the execution plan look like, how will JOINs be processed, is the query using the correct indexes, or is it creating a temporary table? In this blog post, we’ll look at the EXPLAIN command and see how it can help us answer these questions.