The latest from the MySQL community

Percona Toolkit’s pt-online-schema-change (pt-osc) has long been the preferred solution for performing online schema changes with minimal downtime. Its chunk-based copy algorithm is designed to adapt dynamically to the workload, making it suitable for very large tables in production environments.

However, under specific conditions, one of its optimization mechanisms can become counterproductive.

During a customer engagement involving Percona XtraDB Cluster (PXC), we investigated a case where running pt-online-schema-change with a selective –where clause caused severe Galera Flow Control and general overhead, effectively stalling the cluster for an extended period. The issue was not caused by the schema change itself, but by the interaction between:

• adaptive chunk auto-resizing
• highly selective copying of the newest rows
• clustered replication in Galera
• InnoDB …

A while ago, we discussed the cross-site replication feature of the Percona PXC operator. Recently, a similar cross-site replication feature was introduced in the Percona (PS MySQL) operator v1.2.0, a topology based on Group Replication/InnoDB Cluster.

In this blog post, we will explore how to add a DR Cluster to an existing DC Cluster to form a ClusterSet environment, which provides a seamless switchover between DC/DR members. The good part is that all the complexity and configuration will be managed by the Percona operator, with very few setup steps required.

Group Replication …

Percona Server for MySQL now ships with a fully open source OpenID Connect (OIDC) authentication plugin, available starting with Percona Server for MySQL 8.4.11-11 and 9.7.2-2 (not yet released as of this writing). It allows a MySQL account to authenticate against any standards-compliant Identity Provider (IdP) instead of relying on a locally stored password, closing the gap with MySQL Enterprise Edition, which has offered OIDC authentication since MySQL 9.1 and, in several respects, going beyond it.

Oracle offers the same category of functionality, but its server-side plugin is part of the paid MySQL Enterprise Edition. Percona’s implementation is open source and adds three capabilities the Enterprise plugin does not provide: automatic signing-key synchronization from a JWKS endpoint, IdP group-to-role mapping, and proxy-user support. This article explains how the plugin works and why those differences …

Our first post showed MySQL 9.7 with one change: mark a table ENGINE=DuckDB and its analytical queries run in DuckDB instead of InnoDB. The question we kept getting after that was about replication. Can you keep a normal InnoDB primary for the writes, and run a replica where the big tables are ENGINE=DuckDB? Then the heavy reports run on a column store, and ordinary MySQL replication keeps it current. No export job. No second database to sync by hand.

So we tried it. The first run failed, and it failed in a way that is easy to miss: the replica took every transaction, reported success, and stored nothing. We tracked down why, fixed it, and the whole test suite passes now. This post is what we tested, how we checked it, the bug we found, and where it stands.

It’s still an experiment, not production software. The code and the test harness are on GitHub under GPLv2: …

Upstream MySQL published an out-of-schedule release this week with two high-severity CVE fixes. If you’re running Percona Server for MySQL 5.7 or 8.0 under Extended Lifecycle Support (ELS), the program we previously called Post EOL Support, you don’t have to do anything to qualify for them. We’ve already applied the fixes and re-released the affected ELS builds.

This is the point of ELS. When a major version reaches End of Life (EOL), the community stops shipping patches, but the databases running on it don’t stop mattering. ELS keeps critical bug and security fixes coming for versions that are past their EOL date, so you can stay on 5.7 or 8.0 on your own timeline instead of a deadline someone else set.

What we did

These CVE fixes landed upstream outside the normal cadence. Under ELS, customers are entitled to security fixes for the versions they run, so we pulled the patches into the 5.7 and 8.0 builds and …

Managing data retention policies is one of the most common operational tasks in MySQL.

Applications continuously generate transactional, audit, logging, telemetry, and event data. Over time, these tables can grow to billions of rows, causing:

• Larger backups
• Longer recovery times
• Reduced buffer pool efficiency
• Slower index maintenance
• Increased storage costs
• Degraded query performance

To address these problems, organizations typically implement retention policies based on dates or timestamps. Examples include deleting events older than 90 days or purging session data older than 30 days and so forth. The deleted data can then eventually be archived somewhere else, like in another DBMS or on external files.

One of the most widely used tools for implementing these policies in MySQL ecosystems is pt-archiver, part of the Percona Toolkit. …

Percona Monitoring and Management is a great open source database monitoring, observability, and management tool. Query analytics is one of the prominent features DBA uses actively to trace the incidents and query performance identification.

We all know and love the Query Analytics (QAN) dashboard… It’s the first place we look when an incident alert fires or when a developer asks, “Why is the app slow?” or “What was going on during the midnight production outage?”

But sometimes, the standard dashboards just don’t tell the whole story or maybe are not clear enough. QAN is great, but shouldn’t we have more? If you have PMM running, you already have a Ferrari engine under the hood: ClickHouse. Most of us just drive it in first gear using the default UI.

In this post, we are going to take the training wheels off. We will bypass the standard QAN interface and talk directly to the ClickHouse backend to …

Recently, we received an alert for one of our Managed Services customers indicating that the auto_increment value for the table was 80% of its maximum capacity. The column was INT UNSIGNED, which has a limit of 4,294,967,295.

At 80%, we have enough time to change it to BIGINT.…. Right? Let’s see.

So we used pt-online-schema-change to perform the alter.

It started running at a good pace but slowed over time.

Why?

Well, let’s look at the definition of the table:

mysql> show create table myschema.mytableG
*************************** 1. row ***************************
       Table: mytable
Create Table: CREATE TABLE `mytable` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `long_column` …

The latest release of the Percona Operator for MySQL, 1.1.0, is here. It brings point-in-time recovery, incremental backups, zstd backup compression, configurable asynchronous replication retries, and a set of stability fixes. This post walks through the highlights and how they help your MySQL deployments on Kubernetes.

Percona Operator for MySQL 1.1.0

Running stateful databases on Kubernetes means your backup and recovery story has to be airtight. A full nightly backup is fine, until the DBA drops a table at 2 PM and you’re looking at 14 hours of lost work. Or until your storage bill grows faster than your actual data because every backup is a …

Having a separate DR cluster for production databases is a modern day requirement or necessity for tech and other related businesses that rely heavily on their database systems. Setting up such a [DC -> DR] topology for Percona XtraDB Cluster (PXC), which is a virtually- synchronous cluster, can be a bit challenging in a complex Kubernetes environment.

Here, Percona Operator for MySQL comes in handy, with a minimal number of steps to configure such a topology, which ensures a remote side backup or a disaster recovery solution.

So without taking much time, let’s see how the overall setup and configurations look from a practical standpoint.

PXC Cross-Site/Disaster Recovery

DC Configuration

1) Here we have a three-node PXC cluster running on the DC side.

shell> kubectl get pods -n pxc
NAME                                               READY   STATUS …