What index will be used when you count all rows in a table? Well, the MySQL documentation provides a straightforward answer to this, quoting: InnoDB processes SELECT COUNT(*) statements by traversing the smallest available secondary index unless an index or optimizer hint directs the optimizer to use a different index. If a secondary index is […]

We’re excited to announce the availability of Oracle Cloud Infrastructure (OCI) Database Management and Ops Insights services to monitor the on-premises (External) MySQL DB systems! Today, efficient database management is essential to deliver highly performant, reliable, and scalable applications. Database Management in OCI offers a cloud-native, comprehensive database monitoring solution which brings the capabilities of […]

The preFOSDEM MySQL Belgian Days 2025 will occur at the usual place (ICAB Incubator, Belgium, 1040 Bruxelles) on Thursday, January 30th, and Friday, January 31st, just before FOSDEM. Again this year, we will have the chance to have incredible sessions from our Community and the opportunity to meet some MySQL Engineers from Oracle. DimK will […]

The preFOSDEM MySQL Belgian Days 2025 will occur at the usual place (ICAB Incubator, Belgium, 1040 Bruxelles) on Thursday, January 30th, and Friday, January 31st, just before FOSDEM. Again this year, we will have the chance to have incredible sessions from our Community and the opportunity to meet some MySQL Engineers from Oracle. DimK will […]

This article will be helpful if you use the Percona Monitoring and Management (PMM) instance and alert notifications, as it is nice to capture the image of the graph when you receive the alert. We will see how to capture and attach the image of the graph when receiving the alert notification (email, telegram, Slack, […]

Here is part two of my MySQL with Diagrams series (Here’s part one – MySQL with Diagrams Part One: Replication Architecture). We are going to explore how MySQL handles thread termination using the KILL command, as visualized in the provided diagram, and provide sample demonstrations to help you better understand. Many people think they know […]

Did you ever need to determine the performance of a query over time? One of the problems with database query optimizations is that the underlying data is always churning. Add in an increase in the number of users, expanding server demand use, and other items that impact your query. What was optimized is no longer performing as expected.

MySQL added a JSON format option to the output of the EXPLAIN command quite a while ago. More recently, Oracle added the feature of saving the output into a variable (see https://dev.mysql.com/doc/refman/9.0/en/mysql-nutshell.html and https://dev.mysql.com/blog-archive/explain-into-and-explain-for-schema-in-mysql-81-and-82). This provides a way to access the data in that variable and plop it into a database. The saved result can be compared to current or other past responses for analysis. 

mysql> explain format=json into @var
       SELECT * from …

At Percona, we’ve always prioritized performance, and recent trends in MySQL’s development have been a point of concern for us. In particular, the performance deterioration in the MySQL 8.4.x and 9.y versions caught our attention, as highlighted in Marco Tusa’s insightful blog post, Sakila, Where Are You Going? We’re pleased to report that the latest […]

Used to be that replication lag was as simple as Seconds_Behind_Master (renamed to Seconds_Behind_Source). But with multi-threaded replication (MTR) this is no longer the case. It’s time to relearn replication lag monitoring using Performance Schema tables.

Just before the end of the MySQL Advent Calendar, let me announce (or remind you) that MySQL will turn 30 next year!! The first version of MySQL was released in 1995, three decades ago. That database would become MySQL, the open-source relational database management system that has since transformed how developers build and scale applications. […]