A unique constraint specifies, one or more columns as unique it identifies. It is satisfied only when no two rows store the same non-null values at its core. A primary key constraint is a unique one that will say PRIMARY KEY in its defined way. It is satisfied only when rows unfold, and none may […]

When we run databases in Kubernetes, we quickly learn one important truth: things will fail, and we need to be prepared for this. Pods are ephemeral; nodes can come and go, storage is abstracted behind PersistentVolumes and can be either local to a node or backed by network storage, and Kubernetes moves workloads as needed […]

Where We Are We can all agree that the MySQL ecosystem isn’t in great shape right now. Take a look at Julia’s blog post [Analyzing the Heartbeat of the MySQL Server: A Look at Repository Statistics], which confirms what many of us have felt: Oracle isn’t as committed to MySQL and its ecosystem as it […]

The MySQL database server is a foundational component of the open-source world. While its impact is undeniable, looking at the raw statistics of its core source code repository reveals a dynamic and sometimes surprising development history. By analyzing the total lines of code inserted, the number of commits over the years, and unique contributors, we […]

In a recent post, The Quirks of Index Maintenance in Open Source Databases, I compared the IO load generated by open source databases while inserting rows in a table with many secondary indexes. Because of its change buffer, InnoDB was the most efficient solution. However, that’s not the end of the story. Evolution of the […]

Data masking lets you hide sensitive fields (emails, credit-card numbers, job titles, etc.) while keeping data realistic for reporting, support, or testing. It is particularly useful when you collaborate with external entities and need to share your data for development reasons. You also need to protect your data and keep your customers’ privacy safe. Last […]

When you run a simple write, …it may look simple, but under the hood, MySQL’s InnoDB engine kicks off a pretty complex sequence to ensure your data stays safe, consistent, and crash-recoverable. In the top-left corner of the diagram, we see exactly where this begins — the moment the query is executed: [crayon-6947236b4c935379167505/] The log […]

How do you know if your backup is truly reliable? The last thing you want is to discover your data is corrupted during a critical restore or during a migration. While MyDumper is a powerful tool for logical backups, its -M option takes backup integrity to the next level by creating checksums. This often-overlooked feature […]

It may be surprising when a new InnoDB Cluster is set up, and despite not being in production yet and completely idle, it manifests a significant amount of writes visible in growing binary logs. This effect became much more spectacular after MySQL version 8.4. In this write-up, I will explain why it happens and how to address […]

When troubleshooting a MySQL crash, having only the error log is rarely enough to pinpoint the exact root cause. To truly understand what happened, we need to go deeper—into the memory state of the process at the moment it crashed. That’s where GDB, the GNU Debugger, comes in. GDB lets us inspect a core dump […]