The latest from the MySQL community

When setting up a new database for an application, high availability (HA) is one of the main priorities. Let’s assume for this example that you chose to use a Percona XtraDB (PXC) cluster to host your database. But how does the application know which PXC node is healthy and can receive application traffic? Introducing a cluster of ProxySQLs can solve this problem, as ProxySQL will healthcheck the database nodes and route the application traffic to the healthy nodes. However, now the HA problem comes up again: how does the application know which ProxySQL host is healthy?

Putting “one more component” in front of your servers to make them highly available just shifts the problem up by one layer. From making the database HA, to making ProxySQL HA, to needing to make HAProxy HA and so on…

At some point, you may land on the common HA strategy, keepalived, but BGP ECMP is a powerful alternative worth considering.

What …

Two recent posts on the Percona blog caught my attention. In Replicating from InnoDB into a DuckDB storage engine and The DuckDB MySQL engine at 500 GB, Evgeniy Patlan wired DuckDB into mysqld as a storage engine, pointed row-based replication at it, and measured it at TPC-H scale factor 500. The numbers are striking: loads 25 times faster than InnoDB, one fifth of the disk, and the full 22-query TPC-H suite done in 186 seconds where InnoDB needed about 28 hours and never finished four of the queries.

The posts are also honest about the cost. The work is experimental. The worst bug found was silent data loss on every replicated transaction: the two-phase commit code for mixed-engine transactions dropped prepared DuckDB transactions …

Introduction

Many MySQL setups begin life with a familiar incantation:

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innodb_buffer_pool_size = 70% of RAM

…and then nothing changes.

That’s not tuning. That’s a starting guess.

Real tuning starts when the workload pushes back.

Visual Overview

The InnoDB buffer pool is where database performance is quietly decided. It determines whether your workload hums along in memory or drags itself across disk. If you’re not actively observing and tuning it, you’re leaving performance on the table.

This guide walks through how to monitor, understand, and tune the buffer pool using real signals instead of guesswork.

What the Buffer Pool Really Is

The buffer pool isn’t just “memory for MySQL.” It’s a living system under constant pressure:

• A cache of data and indexes
• A write staging area …

MySQL Security Best Practices: A Practical Guide for Locking Down Your Database Introduction

MySQL runs just about everywhere. I’ve seen it behind small personal projects, internal tools, SaaS platforms, and large enterprise systems handling serious transaction volume. When your database sits at the center of everything, it becomes part of your security perimeter whether you planned it that way or not. And that makes it a target.

Securing MySQL isn’t about flipping one magical setting and calling it done. It’s about layers. Tight access control. Encrypted connections. Clear visibility into what’s happening on the server. And operational discipline that doesn’t drift over time.

In this guide, I’m going to walk through practical MySQL security best practices that you can apply right away. These are the kinds of checks and hardening steps that reduce real risk in real environments, and help build a database …

There is a special kind of boredom that only database people know. The kind where you stare at a server humming along and think, surely there is something here I can tune. Good news: there is.

This post walks through the most important MySQL variables to tune for performance, why they matter, and when touching them helps versus when it quietly makes things worse. This is written with InnoDB-first workloads in mind, because let’s be honest, that’s almost everyone.

1. innodb_buffer_pool_size Real metrics to watch

Before touching this variable, look at these:

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SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_read%';

Key fields:

• Innodb_buffer_pool_reads – physical reads from disk
• Innodb_buffer_pool_read_requests – logical reads

…

Configuring the Component Keyring in Percona Server and PXC 8.4

(Or: how to make MySQL encryption boring, which is the goal)

Encryption is one of those things everyone agrees is important, right up until MySQL refuses to start and you’re staring at a JSON file wondering which brace ruined your evening.

With MySQL 8.4, encryption has firmly moved into the component world, and if you’re running Percona Server 8.4 or Percona XtraDB Cluster (PXC) 8.4, the supported path forward is the component_keyring_file component.

The good news: the setup is mostly identical for Percona Server and PXC.
The bad news: PXC 8.4.4 and 8.4.5 shipped with a bug that makes this less fun than it should be.

Let’s walk through a setup that works, keeps your keys locked down, and avoids the usual landmines.

Step 1: Tell …

MySQL replication has been around forever, and yet… people still manage to set it up in ways that break at the worst possible moment. Even in 2025, you can get burned by tiny schema differences, missing primary keys, or one forgotten config flag. I’ve seen replicas drift so far out of sync they might as well live in a different universe.

This guide covers the practical best practices—the stuff real DBAs use every day to keep replication stable, predictable, and boring. (Boring is a compliment in database land.)

Always Use GTIDs. Yes, Always.

GTID-based replication is one of those features that people resist turning on, and then once they do, they never want to go back.

Why GTIDs?

• Failover become sane
• Reparenting replicas stops being a headache
• Missing transactions are easy to detect

Your my.cnf should absolutely include:

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When I first got into woodworking, my mentor shared a piece of advice that has stuck with me ever since: “Use the right tool for the job.” You wouldn’t reach for a belt sander to flatten a board when a planer can accomplish the task faster, cleaner, and with far better results.

The same principle applies in the world of database engineering. When working with MySQL or Percona Server, choosing the correct tool can be the difference between efficient diagnostics and unnecessary downtime.

In this post, I’ll highlight several of the most practical and commonly used utilities from the Percona Toolkit. While the toolkit includes many powerful commands, I’ll focus on the ones that provide the most value in day-to-day operations, troubleshooting, and gathering actionable details for support cases.

PT Summary

A Percona Toolkit utility that provides a concise, high-level overview of a system’s hardware, OS …

In my first post on the MySQL 8.4 Audit Log Filter component, I covered how to install the component and configure a basic filter that captures all events. The Audit Log Filter framework offers a highly granular and configurable auditing mechanism, enabling administrators to log specific events based on criteria such as user, host, or event type. This selective approach enhances observability, supports compliance initiatives, and minimizes unnecessary logging overhead.

In this follow-up, we’ll take a deeper technical look at defining and optimizing audit log filters to capture only the most relevant database activities—delivering actionable audit data while significantly reducing noise and log volume.

Example 1

Audit all events:

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SELECT audit_log_filter_set_filter('log_all_events', …

The audit log filter component in MySQL 8.4 provides administrators with a powerful mechanism for auditing database activity at a fine-grained level. While it offers significant flexibility—such as selectively logging events based on users, hosts, or event types—it can also be challenging to understand and configure correctly.

In this article, we will examine how the audit log filter component works, walk through its core concepts, and share practical tips for configuring and managing audit filters effectively. Our goal is to help you leverage this feature to improve observability, meet compliance requirements, and reduce unnecessary logging overhead.

Enabling Audit Log Filter

We will be using Percona Server 8.4.4 or higher in the examples below. First, we need to enable the audit log filter component. To install the audit log filter component, we need to run the following command:

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